Fractions
Adding and subtracting fractions with unlike denominators
None
Watch the entire video
Adding fractions with unlike denominators
Adding Fractions with Unlike Denominators
Discussion and questions for this video
 We're asked to add 4/9 and 11/12 and to write our answer
 as a mixed number, and then simplify and write our answer
 as a mixed number.
 So here we have two fractions we're adding together, but we
 have different denominators.
 So whenever you add fractions, the first thing you have to do
 is check the denominators.
 If they're the same, you can add, but if they're different
 like this, you have to make them have the same
 denominator.
 So what we have to do is find a number that both 9 and 12
 will divide into, and that will be our common
 denominator, and you'll see why both 9 and 12 have to
 divide into it.
 So let's think about what that number is, and there's two
 ways of coming up with that what we could call a least
 common multiple, the smallest multiple of both 9
 and 12 that is common.
 One way is just to kind of look at the multiples of 9 and
 see if any of them are divisible by 12.
 So if you start with 9 we can do it over here.
 So you have 9, that's not divisible by 12.
 18 isn't divisible by 12.
 27 isn't divisible by 12.
 36, well, that is divisible by 12.
 That is 12 times 3.
 So 9 goes into 36 and 12 goes into 36.
 So what we want to do is write a common denominator.
 So we're going to write 4/9 as something over 36, and we're
 going to write 11/12 as something over 36.
 Now, to turn your 9 into a 36, you have to
 multiply it by 4, right?
 9 times 4 is equal to 36.
 Now, you can't just multiply the denominator by 4.
 You also have to multiply the numerator by the same thing.
 So if you multiply the numerator by 4, you get 4
 times 4 is 16.
 So 4/9 is the exact same thing as 16/36.
 If you wanted to simplify this one to 4/9, you divide the
 numerator and the denominator by 4.
 Now, we do the same thing over here.
 36, 12 times 3, so we're multiplying 12 by 3 to get 36.
 Well, if we did that to the denominator, we also have to
 do that to the numerator, so 11 times 3 is 33.
 And just like that, we've now rewritten each of the
 fractions so that they have the same denominator.
 Both of their denominators is 36.
 So now we're ready to add.
 If you add these two things, we'll have 36, because we're
 considering kind of parts of 36 or fractions of 36, and
 then we have 16 plus 33 in the numerator.
 Let me write that down.
 16 plus 33 in the numerator.
 And 16 plus 33 is what?
 6 plus 33 would be 39 and then you have
 another 10, so it's 49.
 So it's equal to 49/36.
 Now, can we simplify this?
 49, it's 7 squared, so it has 1, 7 and 49 as factors.
 This has 1 it has a bunch of numbers, but it's not
 divisible by 7, so this is actually in simplest form, but
 this is an improper fraction.
 The numerator is larger than the denominator.
 So let's write it as a proper fraction.
 To do that, we divide 36 into 49.
 36 goes into 49 how many times?
 Well, it only goes one time, so it equals 1.
 And how much will be left over?
 If I divide 36 into 49 one time, or 1 times 36 is 36,
 then I have 13 left over to get to 49.
 So it's 1 and 13/36.
 And you can do that manually, if you like you.
 You'd say 36 into 49.
 36 goes into 49 one time.
 1 times 36 is 36, and then you subtract.
 9 minus 6 is 3.
 4 minus 3 is 1.
 You have a remainder of 13.
 So that's our answer: 1 and 13/36.
Be specific, and indicate a time in the video:
At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?

Have something that's not a question about this content? 
This discussion area is not meant for answering homework questions.
why does the denominator have to be the same as the other denominator
Good question.
In mathematics, the concept of adding and subtracting fractions require the denominator to be common. The numerator does not need to be common but the denominator must be.
If the denominator wasn't common how would we work out the question?
E.g. 1/3 + 3/7 = ?
To work out this question, we would have to find the LCM (Lowest Common Multiple) of the denominators; in this case, 3 and 7. Then when we find that it is 21, we can adjust the numerators to 7 and 9. With that done, we can add 9 and 7 to make 16 over the denominator, which is 21.
This is why the denominators have to be common. There was no equation or formula built in the concept of adding and subtracting fractions that do not require the denominators to be common.
I hope this clears everything up. :)
In mathematics, the concept of adding and subtracting fractions require the denominator to be common. The numerator does not need to be common but the denominator must be.
If the denominator wasn't common how would we work out the question?
E.g. 1/3 + 3/7 = ?
To work out this question, we would have to find the LCM (Lowest Common Multiple) of the denominators; in this case, 3 and 7. Then when we find that it is 21, we can adjust the numerators to 7 and 9. With that done, we can add 9 and 7 to make 16 over the denominator, which is 21.
This is why the denominators have to be common. There was no equation or formula built in the concept of adding and subtracting fractions that do not require the denominators to be common.
I hope this clears everything up. :)
It makes the process a lot easier, but you don't have to. Just find the common denominator and multiply, divide, add, or subtract. Using graphs or charts such as the pie chart also helps understand the basic concept of it.
In some cases denominators are equal to make some of the questions easier, like
Example: A person bought 8/10 kgs of sugar and another person bought 2/10 of it. So how much is left in the bag
Answer: Nothing
Example: A person bought 8/10 kgs of sugar and another person bought 2/10 of it. So how much is left in the bag
Answer: Nothing
The denomentar has to be the same because if you want to add , you have to have the same equal sized pieces.
Because the denominator of a fraction can be thought of as a unit and when adding values they have to have the same unit. You can't add inches and centimeters without converting them to the same unit.
Good help now to make another math problem adding multiple fractions eg)1/2 + 3/5 + 4/7= Actually Mom knows the method but the 15 year old can't figure out w/ a lot of examples from a good book. However KHAN makes an excellent teaching explanation!!!
well its not because it makes it esear its just that it wont work properly
It is like the law of sameness. If you add apples and bananas, it is not bananapples, it is fruit.
Because if not, then you won't be able to add or subtract properly and you will get a completely different answer. but if you multiply or divide fraction, you won't need the same denominators. just for adding and subtracting. Hope this Helps!! :)
If the denominators are not the same, then your answer will come out wrong.
For example, say you had 5/6 and 3/4. If you just added them with different denominators, it would come out as 8/10. (4/5), but instead it would be 10/12+9/12=19/12, or 1 7/12.
For example, say you had 5/6 and 3/4. If you just added them with different denominators, it would come out as 8/10. (4/5), but instead it would be 10/12+9/12=19/12, or 1 7/12.
at 2:33 what did he that you have to do mr.
You can't add or subtract unlike denominators unless you find a common denominator
no this has to be wrong make amixed number takes time dont rush him/her
It needs to be like that so you can subtract the numerators you cant do that with different denominators.
Why do you need to make the denominators the same
because say you want to add the 2 numbers the nmbers need to be the same in order to add them witch them means that the numbers need to be the same in order to add them but with subtracting you need to find common numbers that still work in order for you to do the subtracting but if you are multiplying the numbers you still need to find denomiters that will work for both. And for dividing then you need to still need find common denimatiors so then you need to dived the numbers the by the top then the bottom
The integers would have different values and the numerator would be incorrect.
Because you have to make it a least common denominator so you can subtract or add the fraction.
if the denominators are the same it is going to be the denominator in the answer example
3 4ths+2 4ths is going to be 5 4ths but that is a improper fraction
3 4ths+2 4ths is going to be 5 4ths but that is a improper fraction
If the domeator is in the same you can't add it so you need to find what 3 and the 7 have the same multiplies that means you have to multiply 3 times 7 do with the numerator then 7 times 3 then add with numerator then add the numerators and if it is greater then domerator then divided the numerators altogether then tat is you're answer.
Good question.
In mathematics, the concept of adding and subtracting fractions require the denominator to be common. The numerator does not need to be common but the denominator must be.
If the denominator wasn't common how would we work out the question?
E.g. 1/3 + 3/7 = ?
To work out this question, we would have to find the LCM (Lowest Common Multiple) of the denominators; in this case, 3 and 7. Then when we find that it is 21 we can adjust the numerators to 7 and 9. With that done, we can add 3 and 7 to make 10 over the denominator, which is 21.
This is why the denominators have to be common. There was no equation or formula built in the concept of adding and subtracting fractions that do not require the denominators to be common.
I hope this clears everything up. :) GO EVERYONE WHO ANSWERED THIS!
In mathematics, the concept of adding and subtracting fractions require the denominator to be common. The numerator does not need to be common but the denominator must be.
If the denominator wasn't common how would we work out the question?
E.g. 1/3 + 3/7 = ?
To work out this question, we would have to find the LCM (Lowest Common Multiple) of the denominators; in this case, 3 and 7. Then when we find that it is 21 we can adjust the numerators to 7 and 9. With that done, we can add 3 and 7 to make 10 over the denominator, which is 21.
This is why the denominators have to be common. There was no equation or formula built in the concept of adding and subtracting fractions that do not require the denominators to be common.
I hope this clears everything up. :) GO EVERYONE WHO ANSWERED THIS!
It's much better to have them the same denominator because it's way less complex (which means easier). I don't know if there is a way you can add up fractions with unlike denominators but if there is without all the abracadabra, then I'll let you guys know :) But, like I said, it's way less complex if their the same denominator :D Hope this helped. By the way, that's just the way somebody invented fractions _
why? Okay.
You can add 3/8+5/8=8/8
fairly easily because the denominators are the same.
However, if you did not change the denominators then this is what it would be like:
2/8+3/5=?
You cant do it because the denominators are not equal. You can't add 2+3=5
and 8+5=13 and get 5/13. They aren't equal fractions and you don't add denominators.
You can add 3/8+5/8=8/8
fairly easily because the denominators are the same.
However, if you did not change the denominators then this is what it would be like:
2/8+3/5=?
You cant do it because the denominators are not equal. You can't add 2+3=5
and 8+5=13 and get 5/13. They aren't equal fractions and you don't add denominators.
There arae denominator
You cannot add the denominators and when you get the answer you cannot chose a denominator
because it needs a common denominator or the answer will be wrong
i listen the video carefully . the answer is in video
it has to be the same because then we need same denominators for adding fractions with an unlike denominator.
The denominator has to be the same so you can add evenly and so you get the right answer. Hoped it helped
if you add the fractions with unlike denominators it will not be the same as if you change them!
the common factor would me 70 because if you don't find a common factor like the video said its 70
This is a very necessary thing to learn....now I am not as smart as the guy on the videos, but
it is easy to add them when they are alike! It makes it way way way easier! :)
it is easy to add them when they are alike! It makes it way way way easier! :)
I think it's in 0:19
Because to add them they need to have like denominators so you cant just subtract the numerator
It would be like going to the store and saying I want 2/grapes plus 2/apples. They cant bring you out 4/apples or 4/grapes and say that they have satisfied your order. Same thing with fractions with differing denominators. Nor could they say that grape flavored/apples is the same thing as an apple flavored/grapes. They have totally different tastes and sizes depending on what is on the top/bottom ;)
So that you can get the wright number
Imagine we'v got 2 identical apples: apple A and apple B (The denominator is the total number of pieces in each case and the numerator is the number of pieces out of the whole we are working with in each case) :
1.We cut apple A into 2 pieces of the same size and we cut apple B into 8 pieces of the same size.
2. You will agree with me that the one piece of apple A will be larger in size than one piece of apple B.
3. If we represent one piece of apple A in terms of fraction, we'll get 1/2. (Meaning 1 piece of apple out of the 2 pieces. The denominator represents the total no. of pieces)
If we represent one piece of apple B in terms of fraction, we'll get 1/8. (Same logic. Remember we cut apple B in 8 pieces)
4. Since one piece of apple A is not of the same size as one piece of apple B, we cannot add them and get a number directly. We cannot say 1/2 + 1/8= 2/10. (meaning we cannot say that a piece of an apple divided by 2 and another of an apple divided by 8 when added will give us 2 identical pieces out of 10 identical ones. Remember the denominator represents the number of pieces)
5. To get a number, we need to get the pieces of apple A of the same size as those of apple B. For that, we'll need to reduce apple A to 8 pieces too. Only then can we get identical pieces everywhere and thus add effectively.
6. To reduce apiece of apple A to the same size as one of apple B, we need to divide 1/2 by 1/8. This will give us 4. Each of the 2 pieces of apples in apple A will be cut into 4, thus getting 8 identical pieces. One piece of apple A will therefore represent one eighth of the whole apple.
7. With both apple A and apple B being divided into 8 pieces of the same size, calculations can be effectively carried out. We can easily add 1 piece of apple A with one piece of apple B. We can say 1/8 (of apple A) + 1/8 (of apple B)= 2/8 (meaning 2 identical pieces of apples out of 8 identical ones)
1.We cut apple A into 2 pieces of the same size and we cut apple B into 8 pieces of the same size.
2. You will agree with me that the one piece of apple A will be larger in size than one piece of apple B.
3. If we represent one piece of apple A in terms of fraction, we'll get 1/2. (Meaning 1 piece of apple out of the 2 pieces. The denominator represents the total no. of pieces)
If we represent one piece of apple B in terms of fraction, we'll get 1/8. (Same logic. Remember we cut apple B in 8 pieces)
4. Since one piece of apple A is not of the same size as one piece of apple B, we cannot add them and get a number directly. We cannot say 1/2 + 1/8= 2/10. (meaning we cannot say that a piece of an apple divided by 2 and another of an apple divided by 8 when added will give us 2 identical pieces out of 10 identical ones. Remember the denominator represents the number of pieces)
5. To get a number, we need to get the pieces of apple A of the same size as those of apple B. For that, we'll need to reduce apple A to 8 pieces too. Only then can we get identical pieces everywhere and thus add effectively.
6. To reduce apiece of apple A to the same size as one of apple B, we need to divide 1/2 by 1/8. This will give us 4. Each of the 2 pieces of apples in apple A will be cut into 4, thus getting 8 identical pieces. One piece of apple A will therefore represent one eighth of the whole apple.
7. With both apple A and apple B being divided into 8 pieces of the same size, calculations can be effectively carried out. We can easily add 1 piece of apple A with one piece of apple B. We can say 1/8 (of apple A) + 1/8 (of apple B)= 2/8 (meaning 2 identical pieces of apples out of 8 identical ones)
Or you can think of it in an easy way. Let's say the denominators are very special. Each one is unique. Let's say the denominator 4 is an orange, and the denominator 8 is an apple. You can't add apples and oranges because their values are different in the market. 4 oranges may be $5, but 4 apples could be $6.50.
it is this way so it will be easy
They have to be the same becuase to add or subtact them they have to be equivalent
Its super hard, and only some genius from outer space could answer a fraction problem where the denominators are different. We change it to make it possible and easy for us to solve.
because you can't add apples and oranges!
Wow! you r god!
so you can divide
so that you can add it evenly
61 it is don't say it's wrong just think about it how about 11x11=4
22x22=16
Now 33x33=?
22x22=16
Now 33x33=?
we cannot add the denominator,,,,, so we shall have the denominators same
It makes it easier to add the fractions.
you can only add fractions with same denomenator
because if you dont then you are not ready to add them. They need to be the same unlike when you are multiplying fractions
You'll get the awnswer wrong if you don't
so you can add or subtract it, realy pay attention !
I agree with everyone else
that is not logical Zach !
What does it mean to simplify the problem?
Simplifying a fraction just means putting it into the simplest form. For example, 3/6 can be simplified to just 1/2. They are the same thing, but 1/2 is simplified.
To simplify means to reduce the fraction. Like for example, simplify: 4/8.
So you simplify 4/8 to 1/2.
So you simplify 4/8 to 1/2.
Simplifying is just making the fraction smaller
ok when he says to simplify he means that u need to make the fraction into its lowest terms lets say u have 10/20 it becomes 5/10 then it becomes 1/2 it just means to make it small like break it up and to do so u need to make a factor rainbow i believe
Bingo your right k?
You just divide the numerator (top number) and the denominator (bottom number) by the same umber until you can divide no more. Remember you can not have decimals.
It works like this. And I'll use a fraction OTHER than 1/2.
If you have a fraction like 40/120 in a problem on Khan Academy, it won't accept it as an answer. It has to be in simplest form, simply because it's easier to grade for teachers, the website, and you. It simplifies to 1/3 because you can break it down.
If you have a fraction like 40/120 in a problem on Khan Academy, it won't accept it as an answer. It has to be in simplest form, simply because it's easier to grade for teachers, the website, and you. It simplifies to 1/3 because you can break it down.
Simplifying is to take, say 2/4, and to make it into its simplest form which in this case, would be 1/2
well its like 50/100 is half is written like 1/2 and 100 divided by 50=2
50 divided by 50=1
so the numerator is 1 and the demonator is 2 (1/2(half))
50 divided by 50=1
so the numerator is 1 and the demonator is 2 (1/2(half))
One reason is the simplicity principle, keep it simple.
So isn't 1/2 easier to remember and deal with that 108/216 ?
So isn't 1/2 easier to remember and deal with that 108/216 ?
Ex. 4/8 can be simplified into 1/2
4 and 8 can be divided by 4
4 divided by 4 = 1
8 divided by 4 = 2
= 1/2
Remember to divide both the numerator and the denominator by the same number :)
4 and 8 can be divided by 4
4 divided by 4 = 1
8 divided by 4 = 2
= 1/2
Remember to divide both the numerator and the denominator by the same number :)
It means that you make the answer as small as possible. You reduce the answer to the lowest term.
Just what Isaac said. It also means that you need to make it into the smallest fraction as possible. For example, 4/8 would be simplified into 2/4 which would then, make it into 1/2. Then you're done
Simplifying means that you put a number that can be multiplied evenly to get the simplest answer.
You divide the numerator and the denominator by the same number. If the numerator or the denominator don't share any common factors, you're done. If not, divide them both by another (or the same) number until you run out of factors. Just remember that both of the numbers have to stay as whole numbers.
When you simplify you have to make the fraction into the lowest possible fraction. If you have 4/12 you can simplify it. You can divide them both by two. So that would make the fraction now 2/6. You can simplify it lower by dividing it by two again to 1/3. If the fraction is 5/8 you can't divide it any lower because 5 is a prime number. A prime number can only be 1 and itself. Like five. You can't divide it any lower.
Are you Lauren Davidson ?
It means to make the problem simpler.
Or fraction simpler.
For example if you have 6/8,
6 out of 8 simplifies to 3/4.
Because 6=2*3
8=2*4
The 2s cancel out to be just 1.
So there is just 3/4 left.
Hope this helps:)
Or fraction simpler.
For example if you have 6/8,
6 out of 8 simplifies to 3/4.
Because 6=2*3
8=2*4
The 2s cancel out to be just 1.
So there is just 3/4 left.
Hope this helps:)
You have to find the greatest common factor of the numerator and the denominator of the fraction you are simplifying (GCF). Like in the example 4/8 = 1/2, I listed the factors of four and eight. Four: 1,2,4 and eight: 1,2,4,8. Then I listed the common factors. Those are the factors that both numbers have. In this case, 1,2, and 4. Then I select the largest one(4), so as to make the fraction in simplest form. Then I divide both the numerator and the denominator of the original fraction; 4/4=1, 8/4=2. And there you have the fraction in simplest form; 4/8=1/2.For more info see http://www.mathisfun.com/simplifyingfractions.html
Hope this helped,
Tesla
Hope this helped,
Tesla
simplifying is just means to make the problum easier like you divide the nuemerator and denomenatr by the same number.hope it any body who does not know what it means.
thanks but can u tell me how it works
when im adding uncommon fractions, i keep getting it wrong. what im saying is i dont understand. please tell me the steps.
Well, let's do 17/10 + 3/2.
The first step is to find the least common multiples of the denominators ( 10 and 2).
The LCM of 10 and 2 is 10.
You have to multiply 10 1 time to get 10 so you also multiply the numerator by 1. The left side becomes 17*1/10*1
You have to multiply 2 5 times to get 10 so you also multiply the numerator by 5. The right side becomes 3*5/2*5
Your expression is now 17*1/10*1 + 3*5/2*5. 17*1=17. 10*1=10. The left side is now 17/10. 3*5=15 and 2*5=10. The right side is now 15/10.
Your final equation becomes 17/10 + 15/10. Now you add the numerators. 17 + 15 = 32. Your answer is now 32/10.
Now, you simplify. 32/2=16 and 10/2=5. Your final improper answer is 16/5.
The reason it may say you got the question wrong is because you have to convert to a mixed number. 16 goes into 5 3 times. 5*3=15. 16  15 = 1.
Your final mixed answer is 3 1/5.
I hope this was not too confusing :)
The first step is to find the least common multiples of the denominators ( 10 and 2).
The LCM of 10 and 2 is 10.
You have to multiply 10 1 time to get 10 so you also multiply the numerator by 1. The left side becomes 17*1/10*1
You have to multiply 2 5 times to get 10 so you also multiply the numerator by 5. The right side becomes 3*5/2*5
Your expression is now 17*1/10*1 + 3*5/2*5. 17*1=17. 10*1=10. The left side is now 17/10. 3*5=15 and 2*5=10. The right side is now 15/10.
Your final equation becomes 17/10 + 15/10. Now you add the numerators. 17 + 15 = 32. Your answer is now 32/10.
Now, you simplify. 32/2=16 and 10/2=5. Your final improper answer is 16/5.
The reason it may say you got the question wrong is because you have to convert to a mixed number. 16 goes into 5 3 times. 5*3=15. 16  15 = 1.
Your final mixed answer is 3 1/5.
I hope this was not too confusing :)
1/2+3/4=? lets try that. well the denominator needs to be the same so we have to find a common mutiple of 2 and 4. they both go into 4. so, 1/2 becomes 1/4. but, since 2x2=4,we have to mutiply 1 by to also. so, we end up with 2/4. 3/4 stays the same because we are using 4 as the denominator. 4x1=4, and 3x1=3. so, we end up with 2/4+3/4=? well, you only add the numorators, so that would be 5/4. but, the numorator is larger than the denominator. so, you look at the denominator,which is 4, and subtract the numorator,which is 5. so, the final answer is 1 1/4. hope this helps. if not, please comment me about it.
help adding and subtracting
Well it has to equal 1.So say 2/4 and 4/6 jbj;sgkdxf
still not sure have problem 12/18 + 5/6 = Not sure of answer 1 9/18
You're correct! Just make sure to reduce 9/18 to 1/2, so your final answer is 1 1/2.
Thanks for your help now i understand. :)
Why do the denominators have to be the same?
You do not have to make them the same but it makes it far easier to do.
Because the denominator of a fraction can be thought of as a unit and when adding values they have to have the same unit. You can't add inches and centimeters without converting them to the same unit.
Because if you add them it messes up the question
They have to be the same because if you imagine it just drawn in your head then that would not make sence! LIke, for ex:3/5+8/11. Then really if you do it that way then the awenser would be 11/14.
so that you can subtract or add them together
The denominators "denote" what the fraction is counting by (who many is in a whole). This is how we know what portion of a group is selected. For example: I have 10 marbles and 5 of them are blue. What fraction of marbles are blue? 5/10. The denominator being the total number in the group and the numerator being how many.
Now if I were asking to add the number of blue marbles to the number of marbles that you don't know the color of, you would say 5/10 + 5/10 = 10/10 or 1.
This being true we can see that we are adding numerators of the same grouping.
IF this were not true, i.e. adding numerators without like denominators we would get an answer that didn't make sense.
ex. 1/10 + 2/100= ? if you said 3/100. Let's think of money with this example. It would be the same as saying 1 dime plus 2 pennies equals 3 pennies and we know that's incorrect. Therefore, we have to trade the dimes in for pennies giving us 10/100 + 2/100= 12/100. Which makes sense because we know that 1 dime can trade in for 10 pennies and 10 pennies + 2 pennies would equal 12 pennies. I hope this helps.
Now if I were asking to add the number of blue marbles to the number of marbles that you don't know the color of, you would say 5/10 + 5/10 = 10/10 or 1.
This being true we can see that we are adding numerators of the same grouping.
IF this were not true, i.e. adding numerators without like denominators we would get an answer that didn't make sense.
ex. 1/10 + 2/100= ? if you said 3/100. Let's think of money with this example. It would be the same as saying 1 dime plus 2 pennies equals 3 pennies and we know that's incorrect. Therefore, we have to trade the dimes in for pennies giving us 10/100 + 2/100= 12/100. Which makes sense because we know that 1 dime can trade in for 10 pennies and 10 pennies + 2 pennies would equal 12 pennies. I hope this helps.
if you do not make the denominators the same.... it will be hard to do.
if you make them the same...it will be eaiser
if you make them the same...it will be eaiser
because it wont make scene.
Speeds up the process.
how is he correct?
they make the adding process much easier. and drawing pie charts also helps to grasp the concept.
0:00 to 4:05 he is correct!
yeah id do it because its easyer
Imagine we'v got 2 identical apples: apple A and apple B (The denominator is the total number of pieces in each case and the numerator is the number of pieces out of the whole we are working with in each case) :
1.We cut apple A into 2 pieces of the same size and we cut apple B into 8 pieces of the same size.
2. You will agree with me that the one piece of apple A will be larger in size than one piece of apple B.
3. If we represent one piece of apple A in terms of fraction, we'll get 1/2. (Meaning 1 piece of apple out of the 2 pieces. The denominator represents the total no. of pieces)
If we represent one piece of apple B in terms of fraction, we'll get 1/8. (Same logic. Remember we cut apple B in 8 pieces)
4. Since one piece of apple A is not of the same size as one piece of apple B, we cannot add them and get a number directly. We cannot say 1/2 + 1/8= 2/10. (meaning we cannot say that a piece of an apple divided by 2 and another of an apple divided by 8 when added will give us 2 identical pieces out of 10 identical ones. Remember the denominator represents the number of pieces)
5. To get a number, we need to get the pieces of apple A of the same size as those of apple B. For that, we'll need to reduce apple A to 8 pieces too. Only then can we get identical pieces everywhere and thus add effectively.
6. To reduce apiece of apple A to the same size as one of apple B, we need to divide 1/2 by 1/8. This will give us 4. Each of the 2 pieces of apples in apple A will be cut into 4, thus getting 8 identical pieces. One piece of apple A will therefore represent one eighth of the whole apple.
7. With both apple A and apple B being divided into 8 pieces of the same size, calculations can be effectively carried out. We can easily add 1 piece of apple A with one piece of apple B. We can say 1/8 (of apple A) + 1/8 (of apple B)= 2/8 (meaning 2 identical pieces of apples out of 8 identical ones)
1.We cut apple A into 2 pieces of the same size and we cut apple B into 8 pieces of the same size.
2. You will agree with me that the one piece of apple A will be larger in size than one piece of apple B.
3. If we represent one piece of apple A in terms of fraction, we'll get 1/2. (Meaning 1 piece of apple out of the 2 pieces. The denominator represents the total no. of pieces)
If we represent one piece of apple B in terms of fraction, we'll get 1/8. (Same logic. Remember we cut apple B in 8 pieces)
4. Since one piece of apple A is not of the same size as one piece of apple B, we cannot add them and get a number directly. We cannot say 1/2 + 1/8= 2/10. (meaning we cannot say that a piece of an apple divided by 2 and another of an apple divided by 8 when added will give us 2 identical pieces out of 10 identical ones. Remember the denominator represents the number of pieces)
5. To get a number, we need to get the pieces of apple A of the same size as those of apple B. For that, we'll need to reduce apple A to 8 pieces too. Only then can we get identical pieces everywhere and thus add effectively.
6. To reduce apiece of apple A to the same size as one of apple B, we need to divide 1/2 by 1/8. This will give us 4. Each of the 2 pieces of apples in apple A will be cut into 4, thus getting 8 identical pieces. One piece of apple A will therefore represent one eighth of the whole apple.
7. With both apple A and apple B being divided into 8 pieces of the same size, calculations can be effectively carried out. We can easily add 1 piece of apple A with one piece of apple B. We can say 1/8 (of apple A) + 1/8 (of apple B)= 2/8 (meaning 2 identical pieces of apples out of 8 identical ones)
if they arent the same you cant add or subtract
Because when you add or subtract you only add or subtract the numerator, and not the denominator. If you have a different denominator for each fraction, say you had 3/4 + 18,
you can, not, add the denominator AND numerator, because if you do, you get 6/12, which is the wrong answer and if that was the way we added fractions it would be way too easy.
So you need to find the common denominator, by listing the two denominators for each fraction:
4:
8:
then writing out the multiples,
4: 4, 8,
8: 8,
then once you find a common multiple, that common multiple becomes the denominator:
3/8 + 1/8
And since you changed the denominator for one of the fractions, you change the numerator for that fraction, according to the difference for what that fraction's denominator used to be, to what it now is:
3/4 > 3/8
4 x 2= 8
So then you do that change to the numerator to even it out:
In 3/4, the numerator is= 3
So you do 3 x 2, which equals 6, so your new fraction and numerator is 6/8.
Now you have 6/8+1/8, and since you ONLY add the numerator, you get 7/8 for your answer.
you can, not, add the denominator AND numerator, because if you do, you get 6/12, which is the wrong answer and if that was the way we added fractions it would be way too easy.
So you need to find the common denominator, by listing the two denominators for each fraction:
4:
8:
then writing out the multiples,
4: 4, 8,
8: 8,
then once you find a common multiple, that common multiple becomes the denominator:
3/8 + 1/8
And since you changed the denominator for one of the fractions, you change the numerator for that fraction, according to the difference for what that fraction's denominator used to be, to what it now is:
3/4 > 3/8
4 x 2= 8
So then you do that change to the numerator to even it out:
In 3/4, the numerator is= 3
So you do 3 x 2, which equals 6, so your new fraction and numerator is 6/8.
Now you have 6/8+1/8, and since you ONLY add the numerator, you get 7/8 for your answer.
I don't know why I think it's easier
they have to be the same or else you are doing the problem incorrectly. and if you do it incorcorrectly you get an F
they have to be the same or else you can't do it correctly ok patterson?
Why do you have to get the common denominator, can't you just add?
No. If the denominators are unlike you are comparing two completely different things. Think of fractions like pizza. The total number of slices is the denominator. What happens when you increase the total number of slices while keeping the pizza the same size? The slices get smaller. A pizza with 4 slices will have smaller slices than a pizza with just 3 slices. So if you don't keep the denominator (or number of slices) the same your definition of what constitutes a slice (or fraction) changes and your answer no longer makes sense. It maybe easier to comprehend if you see it visualized, checkout http://mathmistakes.info/facts/AlgebraFacts/learn/fr/add.html
You can only add like terms. When you make the denominator and numerator same, the 2 terms are alike. If you know algebra, you must know that you can't add 2 and x unless x has a defined value.
Well, you can but it will become very hard to add something like 5/8+3/16 it's hard right? But with 1/3+2/3, it's one, easy right!
No because if you add you answer would be way off.
The more slices you have, each slice becomes smaller.
Why did he say to turn the nine in to a 36 and why multiply by 4 what.]
nine times four is thirty six but why cant the nine just be nine. I'm confused ):
and why do we have to multiply the numerator by 4 too.~_~
nine times four is thirty six but why cant the nine just be nine. I'm confused ):
and why do we have to multiply the numerator by 4 too.~_~
to add fractions, you need to have the denominator the same. these two fractions have denominators of 9 and 12. The lowest common multiple of these two numbers is 36. That requires multiplying by x4 and x3 respectively. We multiply the numerator and denominator by the same number so the number does not change.
4/9 * 4/4 = 16/36. 4/4 is the same as 1, so the number doesn't change
4/9 * 4/4 = 16/36. 4/4 is the same as 1, so the number doesn't change
at first i felt like you so i know what you mean. If you are multiplying with unlike denominators then you need to multiply the denominators by each other so that they are the same. Then you have to multiply the numerator by the other denominator as to make the number not change. If you didn't , it would be a totally different fraction!
well, you can't really add two uncommon fractions if they don't have a common denominator. And also 12 isn't a multiple of 9! but, they're both multiples of 36 so that's their common denominator!
What about this but for subtracting where is that?
If you understand about adding the fractions together, and changing the denominators, see the video on subtracting fractions. (http://www.khanacademy.org/math/arithmetic/fractions/v/subtractingfractions). There isn't one specifically on subtracting fractions with unlike denominators.
You have to do the same thing, for instance, take 1/3  4/5.
First, list the multiples.
3= 3, 6, 9, 12, 15, 18, 21, 24
5= 5, 10, 15, 20, 25, 30, 35
The least common multiple is 15. So the problem would become ?/15  ?/15. Since 3 times 5= 15, you have to multiply 1 by 5, which = 5. The problem becomes 5/15  ?/15. Since we also multiplied 5 times 3= 15, we have to do that to 4. 4 times 3= 12.
The problem becomes 5/15  12/15.
Because the answer is going to come out negative, here is a trick.
Subtract 12  5. (answer is 7)
Stick a negative sign in (7) and your answer is  7/15.
Hope I Helped! ;D
First, list the multiples.
3= 3, 6, 9, 12, 15, 18, 21, 24
5= 5, 10, 15, 20, 25, 30, 35
The least common multiple is 15. So the problem would become ?/15  ?/15. Since 3 times 5= 15, you have to multiply 1 by 5, which = 5. The problem becomes 5/15  ?/15. Since we also multiplied 5 times 3= 15, we have to do that to 4. 4 times 3= 12.
The problem becomes 5/15  12/15.
Because the answer is going to come out negative, here is a trick.
Subtract 12  5. (answer is 7)
Stick a negative sign in (7) and your answer is  7/15.
Hope I Helped! ;D
yeah, there isn't one for subtracting one with unlike denominators, cuz you do the same thing, but subract . . .
If both denominators are prime numbers, is the only least common multiple between them always going to be the product of the two?
Well, yes because since both are prime numbers, and prime numbers can't divide into each other's multiples, it will have to be the product. For example, 1/5 + 1/7, 7 can't divide into 5's multiples and 5 can't divide into 7's multiples, so the denominator has to be the product. By the way the answer is 7/35 + 5/35 = 12/35
Yes, as long as they are different prime numbers.
just add like this 5/35 + 7/35= 12/35.
If both denominators are prime numbers, is the only least common multiple between them always going to be the product of the two
yes, because two primes don't have any common factors
odfbewjbke'sbjveqbjk'qnrvjkqerv
why does the denominater have to be greater than the top number?
Excellent question my friend. If you had two fractions like 6/5 and 7/5 you would get 13/5. That is what you would call a improper fraction. In arithmetic you wouldn't leave it like that because it's considered a improper fraction. You would need to change it into a mixed number. When you get to algebra 1 they will allow you to leave it as a improper fraction as an answer to a problem.
It's called a improper fraction and there's only 1 strategies to do the problem divide it and get your answer.
add the 7 and the 6 the answer to that will be 13 so divided the 13 and the 5 and that will be the answer.
the denominator must be bigger because the numerator has to go into the denominator.
It doesn't have to but if you are in 5th grade, you haven't learned about that yet. If it is smaller, it is a proper fraction. If the numerator is larger than the denominator, that just means it is an improper fraction and it hasn't yet been reduced into whole numbers.
I don't get this it is hard can anybody help me?
it is quite simple if you ask me all you have do is this Whenever you add fractions with unlike denominators, you must make the denominators of the same value. In this example, the easiest approach is to multiply 8 x 3 to get 24. Here, you multiply by 3 to get . Then you multiply the second equation by 8 to get . Note that both addends have 24 as a denominator. Add in the same manner as with the unit Adding fractions with like denominators.
For adding fractions with unlike denominators, you would need to change the numbers below the bar (denominators) by finding the least common factor/multiple.
Example:
3/4 + 3/16
Convert 3/4 to sixteenths.
4 (4) is 16
3 (4) is 12
Both numerators have to be multiplied by the same numbers.
12/16 + 3/16 = 15/16
Hope this helps!
Example:
3/4 + 3/16
Convert 3/4 to sixteenths.
4 (4) is 16
3 (4) is 12
Both numerators have to be multiplied by the same numbers.
12/16 + 3/16 = 15/16
Hope this helps!
you have to multiply 8 to get 24.
Don't worry I learned this in class. The way I do it is stacking the two fractions then putting equal signs and fraction bars. Multiply the two denominators and that is your Least Common Factor. Then you add the numerators and then BOOM! Awnser is there. Only simplify if directed in math book. JUST evaluate if simplifying not needed.
I don't get your question that you asking me women please be specific but I don't give up so im going to give you the awnser any way............................................... m2;00 so yes
does it take away energy pints to vote
No. Voting is encouraged; in fact, there are badges for it.
no it doesn't khan academy gives you points for everything that you do for then so voting os very okay
Can we do another step like this:
3/8+5/9=(3*9)+(5*8)/72=27+40/72=67/72
3/8+5/9=(3*9)+(5*8)/72=27+40/72=67/72
Yes, that method works perfectly.
3/4 + 1/2=answer in simplest terms
In order to add fractions, the denominators must be the same.
The lowest common denominator or multiple (LCD or LCM) is 4.
Whatever we multiply the denominator by, we must multiply the numerator by.
Therefore, 1/2 = 2/4.
So, 3/4 + 2/4 = 5/4 as an improper fraction or as 1 1/4 as a mixed number.
The lowest common denominator or multiple (LCD or LCM) is 4.
Whatever we multiply the denominator by, we must multiply the numerator by.
Therefore, 1/2 = 2/4.
So, 3/4 + 2/4 = 5/4 as an improper fraction or as 1 1/4 as a mixed number.
The answer is:
1 2/4 or 1 1/2
1 2/4 or 1 1/2
how would you break own 3/5 + 1/11
3/5 + 1/11 = 38/55.
I guess because it is easier to add.
why do you need to multiply the numerator when you multiply the denominator to add or subtract fractions?
Good question. The answer is that if you didn't then you would change the value of the fraction. Like 2/3. If you multiplied both of them by 2, you would have 4/6. Both equal 0.66. If you multiplied the bottom only, then it would be 2/6 which is equal to 0.33. It would change the value.
can both fractions be negativs
Right Patrick Crandon!
check the number line. can you add two negative numbers? the answer is yes.
yes they both can be negtive
yes you can by when you go on the number line and added.
Yes!Negative fractions do exist.
Not helpful pmc,I flagged you as my 2nd flag......
I didn't know you can have negitave fractions!!
JMAtlason
JMAtlason
How do You do tris
The formula is (HOCH^2)^3 CNH^2 , but this is math not chemistry.
Why does the denominator have to be the same as the other denominator?
Think of it this way:
When you are adding or subtracting two things, they must be the same in order to make it work. If you had 6 basketballs, could you subtract 3 iPhones from them? Of course not!
When working with fractions, the denominator describes the SIZE of the piece, so to do the addition or subtraction, you must make them the same size.
The numerator tells you HOW MANY of each "size" you have, so you only add or subtract the numerator, not the denominator (you aren't changing the "size" of the pieces).
Hope this helps.
When you are adding or subtracting two things, they must be the same in order to make it work. If you had 6 basketballs, could you subtract 3 iPhones from them? Of course not!
When working with fractions, the denominator describes the SIZE of the piece, so to do the addition or subtraction, you must make them the same size.
The numerator tells you HOW MANY of each "size" you have, so you only add or subtract the numerator, not the denominator (you aren't changing the "size" of the pieces).
Hope this helps.
i cant understand this, how did you get the x3 but the other x4?
If you're adding a fraction, you must have denominators that are alike. For example, if you are adding 1/4 + 1/3, you have to make both the denominators the same. So the lowest common denominator for 4 and 3 is 12, so you would multiply 1/4 by 3 and get 3/12. Then you would multiply 1/3 by 4 because you need to get the denominator to 12, and 3 times 4 is 12. So you would get 4/12. Now you would add 3/12 and 4/12 together and get 7/12.
I hope this helped and good luck!
I hope this helped and good luck!
Because it is a fraction you can multiply it by anything  it will still be the same fraction of a whole number. (1/2 * 2 is 2/4  but both are 0.5 in decimal terms)
The objective is to get the denominators the same.
The objective is to get the denominators the same.
45= 44
for know we can say * 34 3 g
for know we can say * 34 3 g
It's because the two fractions aren't connected. You can multiply one by three and the other by four and they wouldn't affect each other. As long as the numerators are also being multiplied, you can keep multiplying and switching and dividing forever. I don't usually do this because it only works with a few fractions, and then there's the decimals to worry about, but it can be fun.
Cause we took LCM of both 9 and 12 and they both are divisible by 3 and 3 times 3 = 9 and 3 times 4 = 12
and So, we get x3 and x4
and So, we get x3 and x4
I don't get it at all
i wish your videos would help me but they dont.:(
You can simplify right
you're right.
can you divide fractions
No you can not. You have to flip the right fraction then multiply it. ;)
yes you can beacuse fractions are the answer of 1 divide by a number so yes they can
how do you subtract a broblem
You first use the same method as shown in this video to find common denominators.
Once the denominators are alike, the fractions can be added or subtracted.
Here is a video on "Adding and Subtracting fractions" with like denominators.
http://www.khanacademy.org/math/arithmetic/fractions/Adding_and_subtracting_fractions/v/addingandsubtractingfractions
Once the denominators are alike, the fractions can be added or subtracted.
Here is a video on "Adding and Subtracting fractions" with like denominators.
http://www.khanacademy.org/math/arithmetic/fractions/Adding_and_subtracting_fractions/v/addingandsubtractingfractions
you have to get a common denominator. and then you subtract your two fractions. if possible you need to reduce the fraction.
Do the same as you would with adding, but subtract. Easy!
HI there so i was wondering if someone could help me with my math i really dont understand how to get the answer!
It is this: 3/4+ N= 4/5 and N3/5=1/4
thank you!!
It is this: 3/4+ N= 4/5 and N3/5=1/4
thank you!!
Wait... but lets say you have to add 3 fractions like um.... 1/2 3/4 and 3/8 how would you do that...?
OR
Like what if you had (10 1/2) ( 8 2/3) ( 3 1/3) (5 5/8) how would you do those as mixed numbers...?
OR
Like what if you had (10 1/2) ( 8 2/3) ( 3 1/3) (5 5/8) how would you do those as mixed numbers...?
If you have mixed numbers make them and improper fraction
10 1/2 this is how you convert it into a improper fraction
10x2 = 20
20+1 =21
the answer is 21/2
you get 2 as the denominator because the fraction is 1/2 and the denominator is 2.
10 1/2 this is how you convert it into a improper fraction
10x2 = 20
20+1 =21
the answer is 21/2
you get 2 as the denominator because the fraction is 1/2 and the denominator is 2.
For the first question, you would take 1/2 3/4 and 3/8 and think that eight is the common denominator. If you made 1/2 and 3/4 have 8 as a denominator, then they would be 4/8 and 6/8. Finally, you add 4/8, 6/8 and 3/8 and you would get 13/8 but that is an improper fraction. You take 13 and divide eight into it and get 1 with a remainder of 5. Take the remainder and put it over the eight and the answer is 1 5/8.
You have to find the lowest common denominator. In this case, it is 8. Multiply the fractions so that the denominator becomes 8.
(1/2) would be multiplied by 4, and would become (4/8)
(3/4) would be multiplied by 2, and wold become (6/8)
(3/8) remains the same because the denominator is already 8.
Now, you add the numerators. (1 + 3 + 3) = 7
So the answer would be (7/8)
(1/2) would be multiplied by 4, and would become (4/8)
(3/4) would be multiplied by 2, and wold become (6/8)
(3/8) remains the same because the denominator is already 8.
Now, you add the numerators. (1 + 3 + 3) = 7
So the answer would be (7/8)
yes I believe so
how are fractions used in real life situations?
What if you have five people and one pizza.
The big one I always think of is when you are building something, the measurements are almost always in fractions. Look at any ruler or measuring tape.
It could happen anytime when you have to perform mathematical operations on parts of something.
They are used in telling time, making food, taking medicine, doctors offices, calculating costs, etc, etc, etc!
it could happen when you're cutting a cake
split it in 5 pecies
It is everywhere.
What if you have a problem where one of the fractions has to be divided into a fraction, and the other number is whole?
If one number is whole, you put it over a denominator of 1. If you have 24/8  2, write:
24/8  2/1
Hope this helps!
24/8  2/1
Hope this helps!
you mean like 2/1 divided by 3? if thats what you meant tell me so i can finsih up the answer
Is multiplying a fraction as easy as adding and subtracting one?
no....it is the same but you just multiply in stead of adding and subtracting...
Multiplying is even easier because you don't have to find any common denominators or anything. You just multiply across: the numerator times the numerator and the denominator times the denominator.
It is all the same but instead of subtracting and adding you multiply.
Yes. In real life, multiplying is easier than adding and subtracting, so that probably means that that answer is yes.
Multiplying is actually much easier because you don't need a common denominator.
I still don't understand. Please help me i have test next week.
Well when you add a fraction like 4/6 and 9/10 you have to get a common denominator. To do that multiply the denominator 6x10= 60 now the fraction would look like _/60 all we need to do is fine the numerator 6x what = 60 its 10 then we do 10x4 to get the numerator 40/60 do the same thing to the other one now we got 54/60 + 40/60 ok add the numarator 54+40=94 so now we got 94/60 we need t turn it into a mixed number. How much times can 94 go into 60 its 1 time so now we have 1 and 34/60 and thats not your answer yet you have to reduce. So divided by 2 = 17 then 60 divided by 2 is 30 so 17/30.
cant you use 3 as the donominator ??
Yes you can, but its easier to use the largest number that can go in both numbers because by using the number 3 instead of 12, you would have to keep simplifying over and over.
I was so mad at myself for forgeting how to add fractions but when you came through I was so relived
Dividing and multiplying fractions ??
Indeed, you can divide and multiply fractions.
Let's say I have a piece of pie, which is 1/4 of the whole pie.
I can say: "I'll take two of those pieces", which would be 2x(1/4) = 1/2
Or I could say: "I only need half of this piece", which would mean (1/4) : 2 = 1/8.
But let's say that I have a 1/4piece of a pie, and I want to share my piece with two other people, so each of us would have 1/3 of that 1/4 piece. This would be (1/3) * (1/4) = 1/12. So each of us would get 1/12 of a whole pie.
So it is definitely possible to divide and multiply fractions. If you don't know how it works, I suggest to check out some of Sal's videos on that topic :)
Let's say I have a piece of pie, which is 1/4 of the whole pie.
I can say: "I'll take two of those pieces", which would be 2x(1/4) = 1/2
Or I could say: "I only need half of this piece", which would mean (1/4) : 2 = 1/8.
But let's say that I have a 1/4piece of a pie, and I want to share my piece with two other people, so each of us would have 1/3 of that 1/4 piece. This would be (1/3) * (1/4) = 1/12. So each of us would get 1/12 of a whole pie.
So it is definitely possible to divide and multiply fractions. If you don't know how it works, I suggest to check out some of Sal's videos on that topic :)
Hello! I am a grade 5 student but I really need help with these kind of fractions can you help me?
Perhaps my tutorial shall help?
leftree.webs.com/subtractfractions
leftree.webs.com/subtractfractions
What do you need help with in specific? Finding the common denominator, adding them, or..?
what is the numerator and the denominator?
The top one is called the numerator, the bottom one is called the denominator, and these two numbers are separated by a line.
Example:
2 / 4
2 = numerator
4 = denominator
Example:
2 / 4
2 = numerator
4 = denominator
I am having trouble with converting 2/6 and 14/15 into like denomanators
Think about the denominators: 6 and 30.
Count by 6s (multiples of 6): 6, 12, 18, 24, 30, 36....
Count by 15s (multiples of 15): 15, 30  oh, wait. Stop right there!
30 is the MAGIC NUMBER! It's in both lists. Use 30 as the common denominator.
Ok, so now you convert the fractions:
The 2/6 needs to be multiplied by 5/5 because 6*5=30.
2/6 * (5/5) = 10/30.
The 14/15 needs to be multiplied by 2/2 because 15*2=30.
14/15 * (2/2) = 28/30.
Count by 6s (multiples of 6): 6, 12, 18, 24, 30, 36....
Count by 15s (multiples of 15): 15, 30  oh, wait. Stop right there!
30 is the MAGIC NUMBER! It's in both lists. Use 30 as the common denominator.
Ok, so now you convert the fractions:
The 2/6 needs to be multiplied by 5/5 because 6*5=30.
2/6 * (5/5) = 10/30.
The 14/15 needs to be multiplied by 2/2 because 15*2=30.
14/15 * (2/2) = 28/30.
simplify 1/rt=1/r1+1/r2+1/r3,please show steps on solving thank you
I have no clue how to simplify that! 1/rt=1r1+1/r2+1/r3 does not make sense. Especially cause I am in 5th grade.
Why can't you just put each fractions in the lowest terms before you add like 1/3 and 2/6? I could just simplify 2/6 to 1/3 and equal 2/3. It's still the answer without all the work having to be done at the end. So why can't it be like that?
You can totally add fractions that way  well done.
how do you add a mixed number with an fraction for example 4 2/3 + 1/6
I would first add the fractions so make 2/3 into 4/6 and add that to 1/6.That equals 5/6 and then add that to the whole number (4) to get 4 5/6 as your solution. In other words add the fractions and then add the whole number.
Now it would be 4 5/6.
Change 4 2/3 to 4 4/6. It is the same number and now they have the same denominator. Just add the number 4 just like 1 digit addition.
What do you do if the numerator is odd and the denominator is even because I'm doing homework it tiled adding fractions with mixed numbers
whether the denominator is even or odd does not matter. What matters is whether you can find the greatest common factor to reduce it And if you cannot find one is not affected by it being odd or even. It simply means they have no common factor. For example, 3/42
3 is an odd number but 42 is even.
If you look at their factors. 3 is a factor of itself and a factor of 42.
This would therefore reduce to 1/14.
3 is an odd number but 42 is even.
If you look at their factors. 3 is a factor of itself and a factor of 42.
This would therefore reduce to 1/14.
Because when you add or subtract you only add or subtract the numerator, and not the denominator. If you have a different denominator for each fraction, say you had 3/4 + 18,
you can, not, add the denominator AND numerator, because if you do, you get 6/12, which is the wrong answer and if that was the way we added fractions it would be way too easy.
So you need to find the common denominator, by listing the two denominators for each fraction:
4:
8:
then writing out the multiples,
4: 4, 8,
8: 8,
then once you find a common multiple, that common multiple becomes the denominator:
3/8 + 1/8
And since you changed the denominator for one of the fractions, you change the numerator for that fraction, according to the difference for what that fraction's denominator used to be, to what it now is:
3/4 > 3/8
4 x 2= 8
So then you do that change to the numerator to even it out:
In 3/4, the numerator is= 3
So you do 3 x 2, which equals 6, so your new fraction and numerator is 6/8.
you can, not, add the denominator AND numerator, because if you do, you get 6/12, which is the wrong answer and if that was the way we added fractions it would be way too easy.
So you need to find the common denominator, by listing the two denominators for each fraction:
4:
8:
then writing out the multiples,
4: 4, 8,
8: 8,
then once you find a common multiple, that common multiple becomes the denominator:
3/8 + 1/8
And since you changed the denominator for one of the fractions, you change the numerator for that fraction, according to the difference for what that fraction's denominator used to be, to what it now is:
3/4 > 3/8
4 x 2= 8
So then you do that change to the numerator to even it out:
In 3/4, the numerator is= 3
So you do 3 x 2, which equals 6, so your new fraction and numerator is 6/8.
can the addition be done without changin the denominator ?
No, the denominators must match exactly in order to perform the addition. The only other alternative would be to convert both numbers to decimal form and then add, but then if your answer is supposed to be in fraction form, you would need to convert back to a fraction, which adds more steps and can be difficult to do.
Well, you have to change the unlike denominators to be able to get the answer, but it is possible if you really mastered that subject.
What happens when the denominators don't have a common multiple thing?
You can always find a common denominator.
The easiest way to do it is just to multiply the two denominators together (so 3 and 7 would give you 21 as the common denominator).
Sometimes you can find a better (i.e. smaller) common denominator:
* If you have denominators of 3 and 9, then you can just use 9 as the common denominator (because 3 is a factor of 9).
* If you have denominators of 6 and 4, then you can use 12 as a common denominator (because both 6 and 4 are factors of 12).
What you are looking for, in general, is what's called the *lowest common multiple* of the two denominators.
The easiest way to do it is just to multiply the two denominators together (so 3 and 7 would give you 21 as the common denominator).
Sometimes you can find a better (i.e. smaller) common denominator:
* If you have denominators of 3 and 9, then you can just use 9 as the common denominator (because 3 is a factor of 9).
* If you have denominators of 6 and 4, then you can use 12 as a common denominator (because both 6 and 4 are factors of 12).
What you are looking for, in general, is what's called the *lowest common multiple* of the two denominators.
How do you solve this: (3/7) + (6/11) + (8/21) + (5/22), when there are so many fractions (some negative) with different denominators.
In order to solve this problem you must first find the LCM of all the fractions. The LCM for all of the denominators is 462.
3/7 = 198/462, 6/11 = 252/462, 8/21 = 176/462, 5/22 = 105/462
(198/462) + (252/462) + (176/462) + (105/462) = 125/462
3/7 = 198/462, 6/11 = 252/462, 8/21 = 176/462, 5/22 = 105/462
(198/462) + (252/462) + (176/462) + (105/462) = 125/462
So what if there is no improper fraction. Will you still have to simplify it?? Like for example my daughter has a math worksheet and it says 3/8 + 1/4 and she got 5/8 for the answer but she is trying to figure out a way to simplify it even though it's not an improper fraction
no i dont think you can simplyfy that you will have to try to divide the 5 into the 8
Why do you have to find the reciporical in dividing fractions
When numerator is greater than the denominator.. it is considered as improper fraction?
Yes, when the *numerator* is greater than the *denominator* the fraction is called an *improper fraction*. An improper fraction can also be written as a *mixed fraction*.
For example 8/3 is an improper fraction.
For example 8/3 is an improper fraction.
2 Votes