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## MAP Recommended Practice

### Course: MAP Recommended Practice>Unit 34

Lesson 32: Dividing fractions and whole numbers word problems

# Dividing fractions by whole numbers: studying

Learn to solve a word problem that involves dividing a unit fraction by a whole number. Created by Sal Khan.

## Want to join the conversation?

• So Basically An Reciprocal Is The Opposite?
• Kind of, yes.

You just have to exchange the numerator and denominator for each other to get the reciprocal

For example the reciprocal of 4 would be 1/4, the reciprocal of 1/4 would be 4, and the reciprocal of 2/3 would be 3/2
• When Im dividing fractions and whole numbers (word problems) I always get stumped up on whether or not to keep my answer as a whole number or to add the "1" on top as my numerator. For example- Sally has 1/4 of a tray of brownies. She splits it up between 4 of her friends. How many brownies does each person get? Would my answer be 1/16 or 16? Sorry if this was confusing I'm not that good at explaining things.
• 1/4÷4 would be equal to 1/4×1/4 (flip the second number over). So 1/16 would be the answer. 16 wouldn't be possible because sally only has 1/4 of a tray of brownies; 16 is bigger than 1/4 so 16 is impossible to get
• Kwambok had 30kg of sugar . She put the sugar into packes wagging 3/4 kg each .how many packets did she full?
• Each packet contains 3 ∕ 4 kg, so 10 packets then contains 30 ∕ 4 kg, so in order to get to 30 kg we need 4 ∙ 10 = 40 packets.

– – –

Also, the total weight ∕ the weight of each packet = the number of packets

This gives us 30 ∕ (3 ∕ 4) = 30 ∙ 4 ∕ 3 = 10 ∙ 4 = 40
• at i loved it so much
• I don't get this quite yet could any one help me with this?
• :^| i could help!
the reciprocal is the number flipped. so if you divide lets say, 1/2 by 5, it would be the same thing as multiplying 1/2 by 1/5, which is the reciprocal of 5. then you multiply, giving you 1/10. So, 1/2 divided by 5 is equal to 1/10.
I hope this helped!
Also here's a less math-y way of doing this:

1/2/5
multiply the right two numbers.
1/10
easy right?
• Why does multiplying by a reciprocal is the same than divining fractions? I have not find a video that explains why it works.
• If division is the reverse of multiplication, does this mean that 1/5 x 1/20 = 4?
It is really confusing!'
• 1/5 * 1/20 = (1*1) / (5*20) = 1/100, not 4.

Division is the reverse of multiplication in the sense that: 9*5 = 45. So, then 45/5 = 9 or 45/9 = 5. The division reverses or undos the multiplication.
(1 vote)
• So do you just multiply the denominator of the first fraction and the numerator of the second fraction