Math Help: How to Work Out a Fraction of a Number

To work out a fraction of a number all you need to do is divide the number by the denominator of the fraction and multiply this answer by the numerator.

Example 1

Work out 3/8 of 48.

First of all divide 48 by the denominator:

48 ÷ 8 = 6 (this gives 1/8 of 48)

Now multiply this answer by the numerator:

6 × 3 = 18 (this gives 3/8 of 48)

Example 2

 Work out 2/9 of 36.

First of all divide 36 by the denominator:

36 ÷ 9 = 4 (this gives 1/9 of 36)

Now multiply this answer by the numerator:

4 × 2 = 8 (this gives 2/9 of 36)

Example 3

Work out 4/5 of 60.

First of all divide 60 by the denominator:

60 ÷ 5 = 12 (this gives 1/5 of 60)

Now multiply this answer by the numerator:

12 × 4 = 48 (this gives 4/5 of 60)

Example 4

Work out 5/11 of 77.

First of all divide 77 by the denominator:

77 ÷ 11 = 7 (this gives 1/11 of 77)

Now multiply this answer by the numerator:

7 × 5 = 35 (this gives 5/11 of 77)

Example 5

A fuel tank holds 14 gallons of fuel when full. If the tank has 3/7 of fuel left in the tank, work out how many gallons of fuel are left.

Here you need to calculate 3/7 of 14 gallons

First of all divide 14 by the denominator:

14 ÷ 7 = 2 (this gives 1/7 of 14)

Now multiply this answer by the numerator:

2 × 3 = 6 (this gives 3/7 of 14)

So there are 6 gallons of fuel left in the tank.