Mental percentages

Percentages terrify people unnecessarily. In your head, almost every percentage is built from three friendly blocks: 10%, 5%, and 1% — plus two shortcuts (quarters and the swap trick) for the classic cases.

Learn these and "35% of 240" stops being a calculator question.

Method 1 · Level 1

Percentage Building Blocks: 10%, 5%, 1%

Find 10% (shift the decimal), 5% (half of 10%), 1% (shift twice) — and combine: 15% of 240 = 24 + 12 = 36.

Learn it →

Method 2 · Level 1

Percentage Quarters: 25%, 50%, 75% Fast

25% = halve twice, 50% = halve once, 75% = three of those quarters: 75% of 320 → quarter = 80 → 3 × 80 = 240.

Learn it →

Method 3 · Level 2

The Percentage Swap Trick: X% of Y = Y% of X

Swap the two numbers: 8% of 25 = 25% of 8 = 2. Pick whichever side is easier.

Learn it →

Practice it

Interactive practice

Any method, any difficulty, instant feedback. Generated in your browser.

Start practice

60-second test

One minute, mixed difficulty, personal bests saved on your device.

Take the test

Printable worksheets

Free generator with answer keys — for class or home.

Generate worksheets

Tip: The swap trick alone (X% of Y = Y% of X) turns half of the "hard" percentage problems into one-liners.