Percentage Calculations: All Five Types
Percentages underpin finance, statistics, science, and everyday decision-making. There are five core calculation types — mastering all of them removes uncertainty in any situation involving percentages.
1. What is X% of Y?
Result = Y × (X ÷ 100)
Example: 15% of 240 = 240 × 0.15 = 362. X is what % of Y?
% = (X ÷ Y) × 100
Example: 36 is what % of 240? → (36 ÷ 240) × 100 = 15%3. X is Y% of what number?
Whole = X ÷ (Y ÷ 100)
Example: 36 is 15% of what? → 36 ÷ 0.15 = 2404. Percentage Increase/Decrease
% change = [(New − Old) ÷ Old] × 1005. Finding Original Value After % Change
Original = Current ÷ (1 + % change)
Example: Price after 20% rise is £120 → 120 ÷ 1.20 = £100Mental Maths Tricks
- 10% → move decimal left one place
- 5% → half of 10%
- 1% → move decimal left two places
- 25% → divide by 4
- 33.3% → divide by 3
Solve any percentage problem: Free Percentage Calculator