Math

Percentage Made Easy: Quick Tricks and Formulas

By calculatorfc.online Editorial Team · Updated 2026-05-18

The core percentage formula

To find X% of a number N, multiply: (X ÷ 100) × N. For example, 15% of 200 is 0.15 × 200 = 30.

To find what percentage A is of B, divide and multiply by 100: (A ÷ B) × 100. For example, 30 out of 200 is (30 ÷ 200) × 100 = 15%.

Percentage change = ((new − old) ÷ old) × 100. A price rising from 80 to 100 is a (20 ÷ 80) × 100 = 25% increase.

X% of Y equals Y% of X — so 8% of 50 is the same as 50% of 8 = 4. To find 10%, just move the decimal one place left.

Percentages power discounts, tips, GST/VAT, interest and exam scores — the same simple formula applies everywhere.

Skip the manual math — use our free Percentage Calculator to get instant results.

How do I add a percentage to a number?

Multiply the number by (1 + X/100). To add 18% to 500: 500 × 1.18 = 590.

How do I remove a percentage?

To remove an included X% (like tax), divide by (1 + X/100).