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Lesson 3: Dividing unit fractions by whole numbers

# Visually dividing unit fraction by a whole number

Sal uses area models and number lines to divide unit fractions by whole numbers.

## Want to join the conversation?

• i need a staple so i could staple my staple onto a staple, so i drove to staples to get a staple to staple my staple, so i asked the worker at staples, named mable if they had any staples to staple my staple onto a staple, mabel from staples said she had no staples to staple my staple, so i sat down sad on the ground at staples to look for a free staple until mabel from staples came up to me with a bagel, i looked at mabel from staples and took the bagel and said thank you mabel from staples but then i got a flash back of me and my ex- bestie of us eating bagels outside of a staples pouring maple on our bagles out side of staples! so i ran to my house outside of staples with my bagel with the memory of me pouring maple on my bagel, as soon as i got home i dropped my bagel on the ground and fell, until.. suddenly.. I FOUND A STAPLE TO STAPLE MY STAPLE so i sat down on a chair and at my bagel with maple besides my staple. but then my staple was gone, and i ended up eating my staple. then i died. The end. :)
• i cant understand the topic
• To divide a unit fraction by a whole number:

1) Write 1 in the numerator.

2) Write the product of the unit fraction’s denominator and the whole number, for the new denominator.

Example: let’s divide 1/5 by 8.

The numerator is 1.
The new denominator is 5 x 8 = 40.

Have a blessed, wonderful day!
• How would you show it on a number line, though?
• you take the reciprocal of 3/1 which is 1/3 and then you would do 1/3 x 1/5 and get 1/15 and then you take the denominator and put the denominator as the total number of points and split it into 3 groups of 5.
• this is kinda hard. is it to you?
• It's not super hard once you understand it.
• easiest way to divide fractions by whole numbers: instead of dividing the numerator multiply the denominator for example: 1/5 divided by 3: step 1: 5x1 = 5 5x2 = 10 5x3 = 15 so 1/5 divided by 3 is 1/15 but you shouldn't multiply the numerator along with the denominator
• How I do it is like this. For example 1/5 divided by 7. First write it down. 1/5 divided by 7. then you multiply by making the 7 a fraction like this. 1/5 divided by 1/7. Now just multiply 5 times 7. witch is 35. then just write the 1 on top of the 35. or just write the 1 first like this 1/35 and that is how you do it!
• Did you just type in division instead of multiplication? That’s a very bad mistake, and is little bit rare. Cause 1/5 divided by 1/7 is 7/5. To divide 1/5 divided by 7, you keep the dividend aka the one you’re going to divide, change the division symbol to multiplication, and flip the fraction. Since 7 can be written into 7/1, the reciprocal of 7 is 1/7. So you’re now onto 1/5 times 1/7. The rule of multiplying fractions is to multiply the numerators together and multiply the denominators together. 1 times 1 is 1 and for third graders, 5 times 7 is 35 because (5 times 5) plus (5 times 2) is 25 plus 10 which is 35. So the quotient which you correctly stated, is 1/35.
(1 vote)
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