Start with 10%
Move the decimal point one place to the left. 10% of 240 is 24. 10% of 65 is 6.5.
Build the rest from 10%
- 20%: double the 10%
- 5%: halve the 10%
- 15%: add the 10% and the 5%
- 30%: triple the 10%
Example: 15% of 200. 10% is 20, 5% is 10, so 15% is 30.
Quick fractions
- 50% is half
- 25% is a quarter
- 75% is three quarters
- 20% is a fifth
- 1% is moving the decimal two places
Flip the numbers
X% of Y is the same as Y% of X. So 4% of 75 is the same as 75% of 4, which is 3. Choose whichever is easier.
Check your answer
Use the percentage calculator to confirm results while you build the habit.