What is a percentage?
Percent means out of 100. The sign is %. So 50% means 50 out of every 100, which is one half.
Key idea
To change a fraction over 100 to a percent, keep the top number and add %. 25/100 = 25%. Also ½ = 50% and ¼ = 25%.
Percentage of a quantity
To find 25% of a number, that is the same as finding one quarter of it.
Worked example
Find 25% of 80.
25% = ¼, so take one quarter: 80 ÷ 4 = 20.
Check: 20 × 4 = 80. Correct!
Decimals and percent
0.3 is 3 tenths, the same as 30 hundredths, so 0.3 = 30%.
Percentages are everywhere: a shop may give 10% off, or a test may be marked out of 100. To find 10% of a number, divide it by 10. To find 50%, take half. These shortcuts make percentages quick to work out in your head.
Remember that 30% means 3 lots of 10%, so first find 10%, then multiply by 3.
Remember
- % means out of 100.
- 50% = ½, 25% = ¼, 10% = one tenth.
- 100% is the whole thing.