# GCSE Maths Unit 1 - Percentages

##### November 17, 2015

**GCSE Maths – Percentages **

A percentage is a standardised form for a fraction, in which it is quoted as a fraction of 100. To change a percentage into a decimal or a fraction we divide it by 100%; to change a decimal or a fraction into a percentage we multiply it by 100%.

**Examples**

To get a percentage of a number, multiply the number by the percentage expressed as a fraction or a decimal.

**Examples**

To express one number as a percentage of another, write the two numbers as a fraction and multiply by 100%.

**Example**

Express 117 as a percentage of 500:

To calculate a percentage change (either increase or decrease) use the formula

Percentage change =

[NB:** **A very common mistake is to use the new value instead of the original value]

**Example**

A company had expected sales of £15,000 last month, but when the actual sales for the month were totalled they came to £17,280. By what percentage did the actual sales exceed the expected?

Increase = £17,280 – £15,000 = £2,280, so percentage increase = × 100% = 15.2%

### Work Towards That 'A' Grade

Achieve the results you want with-written revision resources when you register with iRevise. **Its Free!**