If you have to add a fraction by a whole number can we just add the number and not turn it into a fraction?

Yes. This will create what math likes to call a 'mixed number', at least, when you're adding. Take this example: You order two large pepperoni pizzas for a big party you're throwing with your friends. They eat a few slices, and you're left with only two thirds for one pizza. However, the other pizza is still whole. We can solve this problem by creating a mixed number, which is made by simply adding a whole number and a fraction together, like so: one and two thirds. You can also express it as 1 2/3 or 1+2/3. Hope this helped.

i stil dont get how 2/3 times 6 is equal to 4

Whenever you have a series of mulitplications and divisons they are meant to be done left to right. In this case, 2/3 = 0.666.... repeating. 0.6666... x 6 = 3.9999....6. The reason for this number is that the 0.666 is meant to be endless. The more 6s you would add, the closer the result would be to 4. Another way to do this, which is more precise, would be to treat the numbers as fractions, 2/3 x 6/1. In this case, 2x6 = 12, then 12/3 = 4. We cannot do 2/(3x6) because that would be the same as multiplying by 1/6, not 6/1.

Is there another way to do this?

The easiest way to think about multiplying fractions by whole numbers is to multiply the numerator of the fraction by your integer and then bring over the deonominator. 3/4 * 8 can be thought of as (3*8)/4, or 24/4, or 6. 1/2 * 7 is (1*7)/2, or 7/2 6/23 * 3 is(6*3)/23, or 12/23

At 0:27, why did he multiply the whole number with a numerator even though we learned to multiply with the denominator can someone describe me please?

This is because sal has 6 2/3, but he wants to add them together, not find a equivalent fraction. You would use the denominator when trying to find an equivalent fraction.

Main content

Course: 5th grade > Unit 6

Lesson 2: Multiplying fractions and whole numbers

Multiplying fractions and whole numbers

Name: Multiplying fractions and whole numbers
Uploaded: 2013-10-24T21:27:37Z
Description: Multiplying fractions is about combining parts of a whole. When you multiply two fractions together, you're taking a part of a part. When you multiply a fraction by a whole number, you're taking multiple copies of that fraction. In both cases, the result is a new fraction that represents a different part of a whole.

Google Classroom

Multiplying fractions is about combining parts of a whole. When you multiply two fractions together, you're taking a part of a part. When you multiply a fraction by a whole number, you're taking multiple copies of that fraction. In both cases, the result is a new fraction that represents a different part of a whole. Created by Sal Khan.

Want to join the conversation?

Sort by:

Hobbs Conor
Posted 6 years ago. Direct link to Hobbs Conor's post “If you have to add a frac...”
If you have to add a fraction by a whole number can we just add the number and not turn it into a fraction?
Button navigates to signup pageComment on Hobbs Conor's post “If you have to add a frac...”
(40 votes)
Answer
- Caden Cummins
  Posted 6 years ago. Direct link to Caden Cummins's post “Yes. This will create wha...”
  Yes. This will create what math likes to call a 'mixed number', at least, when you're adding.
  Take this example:
  You order two large pepperoni pizzas for a big party you're throwing with your friends. They eat a few slices, and you're left with only two thirds for one pizza. However, the other pizza is still whole.
  We can solve this problem by creating a mixed number, which is made by simply adding a whole number and a fraction together, like so: one and two thirds. You can also express it as 1 2/3 or 1+2/3.
  Hope this helped.
  Comment on Caden Cummins's post “Yes. This will create wha...”
  (31 votes)
Nadia Chibani
Posted 8 years ago. Direct link to Nadia Chibani's post “i stil dont get how 2/3 t...”
i stil dont get how 2/3 times 6 is equal to 4
Button navigates to signup pageComment on Nadia Chibani's post “i stil dont get how 2/3 t...”
(10 votes)
Answer
- Chloe Atallah
  Posted 8 years ago. Direct link to Chloe Atallah's post “Whenever you have a serie...”
  Whenever you have a series of mulitplications and divisons they are meant to be done left to right. In this case, 2/3 = 0.666.... repeating. 0.6666... x 6 = 3.9999....6. The reason for this number is that the 0.666 is meant to be endless. The more 6s you would add, the closer the result would be to 4.
  Another way to do this, which is more precise, would be to treat the numbers as fractions, 2/3 x 6/1. In this case, 2x6 = 12, then 12/3 = 4. We cannot do 2/(3x6) because that would be the same as multiplying by 1/6, not 6/1.
  Comment on Chloe Atallah's post “Whenever you have a serie...”
  (16 votes)
01robotboy
Posted 3 years ago. Direct link to 01robotboy's post “Is there another way to d...”
Is there another way to do this?
Comment on 01robotboy's post “Is there another way to d...”
(6 votes)
- Cavan P
  Posted 3 years ago. Direct link to Cavan P's post “The easiest way to think ...”
  The easiest way to think about multiplying fractions by whole numbers is to multiply the numerator of the fraction by your integer and then bring over the deonominator.
  
  3/4 * 8 can be thought of as (3*8)/4, or 24/4, or 6.
  1/2 * 7 is (1*7)/2, or 7/2
  6/23 * 3 is(6*3)/23, or 12/23
  Comment on Cavan P's post “The easiest way to think ...”
  (11 votes)
Khan
Posted a year ago. Direct link to Khan's post “At 0:27, why did he multi...”
At
0:27
, why did he multiply the whole number with a numerator even though we learned to multiply with the denominator can someone describe me please?
Button navigates to signup pageComment on Khan's post “At 0:27, why did he multi...”
(4 votes)
Answer
- Aspen
  Posted a year ago. Direct link to Aspen's post “This is because sal has 6...”
  This is because sal has 6 2/3, but he wants to add them together, not find a equivalent fraction. You would use the denominator when trying to find an equivalent fraction.
  Comment on Aspen's post “This is because sal has 6...”
  (5 votes)
Lisa
Posted 9 years ago. Direct link to Lisa's post “The way he showed it is f...”
The way he showed it is for people that do not know to use multiplication. I can see how people can get confused on this.
Button navigates to signup pageComment on Lisa's post “The way he showed it is f...”
(4 votes)
Answer
Robert Roy
Posted 6 years ago. Direct link to Robert Roy's post “how do you figure out if ...”
how do you figure out if a question is right or wrong
Button navigates to signup pageButton navigates to signup page
(3 votes)
Answer
Ryker Sparks
Posted 3 years ago. Direct link to Ryker Sparks's post “this is hurting my head i...”
this is hurting my head it not hard it just the fact that it exticts
Button navigates to signup pageComment on Ryker Sparks's post “this is hurting my head i...”
(3 votes)
Answer
Caden Flanagan
Posted 3 years ago. Direct link to Caden Flanagan's post “🥺can you explain it in a...”
🥺can you explain it in a easier way please you made this more difficult🥺
Button navigates to signup pageComment on Caden Flanagan's post “🥺can you explain it in a...”
(3 votes)
Answer
Alessio Pirazzini
Posted 3 years ago. Direct link to Alessio Pirazzini's post “Adding 2/3 together 3 tim...”
Adding 2/3 together 3 times is one way to do it. But you could also multiply 6/1 by 2/3. Right? Because 6 over 1 is six ones so its 6 wholes.
Button navigates to signup pageComment on Alessio Pirazzini's post “Adding 2/3 together 3 tim...”
(3 votes)
Answer
Michaelr.Renaud
Posted 5 years ago. Direct link to Michaelr.Renaud's post “He is demonstrating anoth...”
He is demonstrating another method of finding the fraction of the whole number he used. If 6/6 = 6 then 2/3 = 4/6. Therefore, 2/3 or 4/6 of 6 equals 4 because 4 is 2 out of every 3 in 6. Also, if 3 x 2 = 6, then 2 x 2 = 4 and 2/3 = 4 out of the whole 6
Button navigates to signup pageButton navigates to signup page
(3 votes)
Answer

Video transcript

Let's think a little bit about what it means to multiply 2/3 times 6. One way to think about it is to literally take six 2/3 and add them together. This is six 2/3 right over here. And if we wanted to actually compute this, this would be equal to-- well, we're going to take these six 2's and add them together. So we could view it as 2 times 6 over 3. 2 times 6 over 3, which is the same thing, of course, as 2, 4, 6, 8, 10, 12, 12/3. And what is 12/3 equal to? Well, we could rewrite 12 as-- so this is equal to-- we could rewrite 12 as 3 plus 3 plus 3 plus 3 over the yellow 3. Let me do it like this so I don't have to keep switching colors. This is going to be the same thing as 3/3 plus 3/3 plus 3/3 plus 3/3. And each of these are obviously a whole. Each of these equal 1. That's 1 and that's 1, so this is going to be equal to 4. So that's one way to conceptualize 2/3 times 6. Another way to think of it is as 2/3 of 6. So let's think about that. Let me draw a number line here. And I'm going to draw the number line up to 6. So what I care about is the section of the number line that goes to 6. So that looks pretty good. So this is 1, 2, 3, 4, 5, and 6. So if we want to take 2/3 of 6, we can think of this whole section of the number line between 0 and 6 as the whole. And then we want to take 2/3 of that. So how do we do that? Well, we divide it into thirds, to three equals sections. So that's one equal section, two equal sections, and three equal sections. And we want two of those thirds. So we want 1/3 and 2/3. Now where does that get us? That gets us to 4. So we get, obviously, to the same answer. We would be in a tough situation if somehow we got two different answers. Either way, 2/3 times 6 or 6 times 2/3, either way, that is going to be equal to 4. But there are two different ways of viewing this. This first way is literally viewing it as 2/3 six times. And this way is we're taking a fraction of the number 6. We're going 2/3 of the way to 6, which would get us to 4.