This presentation will help you to: add subtract multiply and divide fractions

To add fractions together the denominator (the bottom bit) must be the same.

Example

8

2

8

1

To add fractions together the denominator (the bottom bit) must be the same.

Example

8

2

8

1

8

21

To add fractions together the denominator (the bottom bit) must be the same.

Example

8

2

8

1

8

21

8

3

Click to see the next slide to reveal the answers.

1. 2.

3. 4.

3

1

3

1

12

7

12

3

7

4

7

2

4

1

4

2

1. 2.

3. 4.

3

1

3

1

12

7

12

3

7

4

7

2

4

1

4

2

3

24

3

7

6

12

10

Subtracting fractions

8

2

8

3

To subtract fractions the denominator (the bottom bit) must be the same.

Example

Subtracting fractions

8

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8

3

8

23

To subtract fractions the denominator (the bottom bit) must be the same.

Example

Subtracting fractions

8

2

8

3

8

23

8

1

To subtract fractions the denominator (the bottom bit) must be the same.

Example

Now try these

Click on the next slide to reveal the answers.

1. 2.

3. 4.

3

1

3

2

12

3

12

77

3

7

4

4

1

4

2

Now try these

.

1. 2.

3. 4.

3

1

3

2

12

3

12

77

3

7

4

4

1

4

2

3

14

1

7

1

12

4

Multiplying fractions

To multiply fractions we multiply the tops and multiply the bottoms

Top x Top

Bottom x Bottom

Multiplying fractions

Example

3

1

2

1

Multiplying fractions

Example

3

1

2

1

32

11

Multiplying fractions

Example

3

1

2

1

32

11

6

1

Now try these

Click on the next slide to reveal the answers.

1. 2.

3. 4.

3

1

3

1

5

3

3

1

5

4

4

2

4

1

4

2

Now try these

.

1. 2.

3. 4.

3

1

3

1

5

3

3

1

5

4

4

2

4

1

4

29

116

2

20

8

15

3

Dividing fractions

Once you know a simple trick, dividing is as easy as multiplying!

• Turn the second fraction upside down

• Change the divide to multiply

• Then multiply!

Dividing fractions

•Turn the second fraction upside down

Example ?3

1

6

1

1

3

6

1

Dividing fractions

•Turn the second fraction upside down

Example ?3

1

6

1

1

3

6

1

•Change the divide into a multiply

1

3

6

1

Dividing fractions

•Turn the second fraction upside down

Example ?3

1

6

1

1

3

6

1

•Change the divide into a multiply

1

3

6

1

•Then multiply

16

31

1

3

6

1

Dividing fractions

•Turn the second fraction upside down

Example ?3

1

6

1

1

3

6

1

•Change the divide into a multiply

1

3

6

1

•Then multiply

16

31

1

3

6

1

6

3

Now try these

Click on the next screen to reveal the answers.

1. 2.

3. 4.

2

1

3

1

5

4

2

1

6

2

4

1

3

2

4

1

Now try these

1. 2.

3. 4.

2

1

3

1

5

4

2

1

6

2

4

1

3

2

4

1

3

28

3

8

6

8

5

To add or subtract fractions together the denominator (the bottom bit) must be the same.

So, sometimes we have to change the bottoms to make them the same.

In “maths-speak” we say we must get common denominators

To get a common denominator we have to:

1. Multiply the bottoms together.

2. Then multiply the top bit by the correct number to get an equivalent fraction

For example ?3

1

2

1

For example

1. Multiply the bottoms together

?3

1

2

1

632

For example ?3

1

2

1

2. Write the two fractions as sixths

6

?

2

1

6

?

3

1

For example

?3

1

2

1

To get ½ into sixths we have multiplied the bottom (2) by 3. To get an equivalent fraction we need to multiply the top by 3 also

For example

?3

1

2

1

To get ½ into sixths we have multiplied the bottom (2) by 3. To get an equivalent fraction we need to multiply the top by 3 also

6

3

6

31

2

1

For example

?3

1

2

1

To get 1/3 into sixths we have multiplied the bottom (3) by 2. To get an equivalent fraction we need to multiply the top by 2 also

For example

?3

1

2

1

To get 1/3 into sixths we have multiplied the bottom (3) by 2. To get an equivalent fraction we need to multiply the top by 2 also

6

2

6

21

3

1

For example

?3

1

2

1

We can now rewrite

3

1

2

1

For example

?3

1

2

1

We can now rewrite

6

2

6

3

3

1

2

1

For example

?3

1

2

1

We can now rewrite

6

2

6

3

3

1

2

1

6

23

For example

?3

1

2

1

We can now rewrite

6

2

6

3

3

1

2

1

6

23

6

1

This is what we have done:

3

1

2

1

1. Multiply the bottoms

6

?

6

?

This is what we have done:

3

1

2

1

1. Multiply the bottoms

6

?

6

?

2.Cross multiply

6

?

6

31

This is what we have done:

3

1

2

1

1. Multiply the bottoms

6

?

6

?

2.Cross multiply

6

21

6

3

6

?

6

31

This is what we have done:

3

1

2

1

1. Multiply the bottoms

6

?

6

?

2.Cross multiply

6

21

6

3

6

?

6

31

6

2

6

3

Now try these

Click on the next slide to reveal the answers.

1. 2.

3. 4.

2

1

3

1

2

1

5

4

6

1

4

3

3

2

4

1

24

14

Now try these

1. 2.

3. 4.

2

1

3

1

2

1

5

4

6

1

4

3

3

2

4

1

6

512

11

24

1410

3

12

7

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