How_To_Be_Good_At_Math

NUMBERS • MULTIPLYING FRACTIONS 55

To multiply fractions we multiply the

numerators to make a new numerator.

Then we multiply the denominators

to make a new denominator.

Now to find one half of the

quarter, we draw a line

through the middle of the four

quarters. By dividing each

quarter in half, we now have

eight equal parts.

For the calculation^1 / 2 ×^1 /4,

let’s say this means “one half

of one quarter”. First, let’s divide

a whole into four quarters and

shade in one quarter.

Let’s shade in the top half of

our original quarter. This

part is one half of a quarter, and

also one-eighth of the whole. So

we can say that^1 / 2 ×^1 /4 =^1 /8.

Multiplying fractions with a fraction wall

When we multiply two fractions together, it can be useful to say that the “×”

symbol means “of”. Let’s find out how this works with the help of a fraction wall.

How to multiply fractions

Let’s look at another way we can

multiply fractions, without drawing

a fraction wall.

Now let’s try with

two non-unit

fractions. The method is

exactly the same – just

multiply the numerators

and the denominators to

find the answer.

Look at this calculation.

Can you see that the

numerators and the

denominators have been

multiplied together to make

the answer?

Multiply the

numerators together

The calculation^1 / 2 ×^1 / 4 is the same

as saying “a half of a quarter”

This section is one half

of the original quarter

1

4

1

2 × =?

1

4

1

2 × =

1

8

1

2

1

6

1

12

4

15

Multiply the

denominators together

1

2

×

×

×

1

× 6

= =

=

1

6

1

2 × =?

2

3

2

5 × =?

Multiply the

numerators together

2

5

2

3

Multiply the

denominators together

2

5

× 2

× 3

=

1 whole

1

4

1

4

1

4

1

4

1

8

1

8

1

8

1

8

1

8

1

8

1

8

1

8

1 whole 1 whole

054-055_Multiplying_Fractions.indd 55 29/02/2016 14:09