Calculating percentages

Percentages are a way of expressing proportion.

Proportion tells you how much of one thing there is in relation to the whole.

'Per cent' means ‘out of 100’ and a percentage is written as a number with the % symbol.

There are some simple techniques to help work out percentages.

One way to find a percentage of an amount is to use 50%, 10% and 1% building blocks.

Complete this interactive activity to better understand how to calculate a percentage. Then put your knowledge to the test.

To find 25%, divide the value you found for 50% by 2.

For example:

40 ÷ 2 ‎ =  20

So, 25% of 80 is 20.

Finding 10%

To work out 10%, divide the number by 10.

For example, to find 10% of 360:

360 ÷ 10 ‎ =  36

To find a multiple of 10%, divide by 10 and then multiply by the number of tens you want to find.

For example, to find 30% of 360, multiply the value you found for 10% by 3.

36 × 3 ‎ =  108

So, 30% of 360 is 108.

You could also find 5%, by dividing 10% by 2.

36 ÷ 2 = 18

So, 5% of 360 is 18.

Finding 1%

For percentages that aren’t a multiple of 10, divide the number by 100 to find 1%.

Then multiply by the number of percent you need to find.

For example, to find 22% of 1200. First divide 1200 by 100 to find 1%.

1200 ÷ 100 = 12

Then multiply by 22, to find 22%.

12 × 22 = 264

So, 22% of 1200 is 264.

Parts of a whole

Fractions, percentages and decimals are all ways to describe parts of a whole.

The sign % stands for 'per cent' which means 'out of 100'.

Fractions can be expressed as percentages and decimals.

For example, a half is 50%, a quarter is 25%, a tenth is 10% and a fifth is 20%.

Example 2

Example 3