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How to find a percentage of a number
"Percent" means out of 100. So 25% means 25 out of every 100. Once you know that, percentages get a lot easier.
The super-handy 10% trick
To find 10% of a number, divide it by 10 (move the decimal point one place left).
10% of 80 = 8
Now build other percentages from it: 20% is double that (16), 30% is three times (24), 5% is half of it (4).
Easy friends: 50%, 25% and 75%
- 50% = half. 50% of 60 = 30.
- 25% = a quarter, so halve it twice. 25% of 60 = 15.
- 75% = 50% + 25%. 75% of 60 = 30 + 15 = 45.
Any percentage: the step-by-step way
- Turn the percent into a fraction out of 100: 15% = 15/100
- Multiply by the number: 15/100 × 80 = 1200/100
- Divide: 1200 ÷ 100 = 12. So 15% of 80 is 12.
Check with the 10% trick: 10% of 80 is 8, 5% is 4, and 8 + 4 = 12. ✓
Try one yourself
20% of 45 = ?
Hint: find 10% first, then double it.
Where you'll see percentages
- Sales: "30% off" at the store.
- Test scores: 18 out of 20 is 90%.
- Your phone or tablet battery!
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