Percentage Calculator
Three common percent questions, with the working shown. Pick the one you need.
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How percentages work
A percent is just a fraction with 100 on the bottom. 25% means 25/100 means 0.25. Every percent question reduces to multiplying or dividing by that decimal.
- X% of Y → (X/100) × Y. "25% of 200" = 0.25 × 200 = 50.
- X is what % of Y → (X / Y) × 100. "40 out of 160" = 25%.
- % change from A to B → ((B − A) / |A|) × 100. From 80 to 100 = +25%.