MATHEMATICSDividing with Fractions

Lesson Objectives

•The aim of this powerpoint is to help you…

• to divide fractions by whole numbers

• to divide whole numbers by fractions

• to divide fractions by fractions

Dividing Fractions

• FIRSTLY convert any mixed numbers into improper fractions or write whole numbers over 1, then…

• Change the divide sign to a multiply and at the same time, swap the top and bottom values of the second fraction!

• Multiply the top numbers together

• Multiply the bottom numbers together

• Cancel down (if possible) and/or convert your improper fraction back into a mixed number

Example 1How many lots of ¾ are there in 3?

3 4

Proof:

÷ = = 3×4 12 1×3 33 ×

3 41 3 4=

In 3 whole ones you have…

…4 lots of ¾

Example 2What is 7/8 divided by 1/2?

7 1 8 2

If you need to simplify your answer…

14 8

÷ = =

÷2

÷2

7×2 148×1 8

7 28 1

×

= 3 41 7

4

Example 3Calculate…

3 1 5 2

8 5 5 2

÷

= =8×2 165×5 25

1 2

÷ 8 25 5

×

As with multiplying fractions, convert any mixed numbers to improper fractions first!

Quick Practice

A 5 3 D 7 3

9 4 10 4

B 11 23 E 5 2

12 24 9 3

C 3 11 F 8 4

8 12 15 5

Work out your answers before clicking on to the next slide.

÷

÷÷

÷

÷÷

Answers

A ÷ × =

B ÷

× =

C ÷

× =

D ÷ × =

E ÷

× =

F ÷

× =

2027

or

or

or

or

or

What next?

• Print out the notes called Frac6. Read them and make sure you answer any questions

• Work through all of the MyMaths lesson called Dividing Fractions found at: http://www.mymaths.co.uk/tasks/library/loadLesson.asp?title=fractions/dividingFractions&taskID=1040

• If you need more practice, try the worksheet called

DFrac-S1.xlsx.

• Now move on to the Frac-7 powerpoint