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Percentage Calculator

Answer the three everyday percentage questions — “what is 15% of 240?”, “36 is what percent of 240?” and “36 is 15% of what?”

Quick answer

X% of Y = X ÷ 100 × Y, so 15% of 240 = 36. To find what percent A is of B, divide A by B and multiply by 100. For change between two numbers, use the percentage change calculator.

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  • Everyday
  • Updated October 2026

15% of 240

36

Show the working
  1. 15 ÷ 100 × 240 = 36

About the Percentage calculator

Almost every percentage problem is one of three questions, built from the same relationship: part = percentage × whole. Pick the question you are asking from the dropdown and the calculator rearranges the formula for you.

Use it for tips, test scores, tax, commission, survey results or checking whether a “40% off” claim adds up.

How to use it

  1. Choose the question you want to answer.
  2. Fill in the two numbers you know.
  3. Read the answer — open “Show the working” to see each step.

The formula

Part = Percentage ÷ 100 × Whole

  • What percent: Percentage = Part ÷ Whole × 100.
  • Find the whole: Whole = Part ÷ (Percentage ÷ 100).

Worked example

A test score

  1. You scored 42 out of 60.
  2. 42 ÷ 60 = 0.70.
  3. 0.70 × 100 = 70%.

Frequently asked questions

How do I work out a percentage of a number in my head?

Find 10% by moving the decimal point one place left, then scale. 15% of 240: 10% is 24, 5% is 12, so 15% is 36.

Is X% of Y the same as Y% of X?

Yes. 8% of 50 equals 50% of 8 — both are 4. Swap them when one is easier to calculate.

How do I calculate percentage increase?

Use the percentage change calculator: subtract the old value from the new one, divide by the old value and multiply by 100.

Results are estimates for planning — check critical figures with a professional or the official source.

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