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Percentage Formulas with Real-Life Examples

Calculate a percentage of a total, the percent one part represents and percentage growth in everyday situations.

Published October 18, 2026

Percentage Formulas with Real-Life Examples

Calculate a percentage of a total, the percent one part represents and percentage growth in everyday situations. Use the free RapidCalc calculator to check your own numbers and explore different inputs.

Percentage of a number

To find p% of N, compute N × p ÷ 100. For example, 15% of 240 is 36.

A part as a percentage of the whole

Part ÷ whole × 100 converts a fraction to percent. If 18 of 60 people choose an option, its share is 30%. The whole must be nonzero.

Percentage increase and decrease

Percent change = (new − old) ÷ |old| × 100, when the original is nonzero. A rise from 80 to 100 is 25%; a fall from 100 to 80 is −20%.

Reverse percentages

For a 20% price increase, final price = original × 1.2. If final price is $120, the original was $100. For a 20% discount, divide the final by 0.8 instead.

Why percentage points differ

A change from 10% to 15% is five percentage points, but a 50% relative increase. Use the right comparison for your question.

Try your own example

Open the interactive calculator and change one number at a time to see the effect. Read the assumptions attached to the result before applying it to a real transaction.

Educational information only; product rules, tax rates and financial terms vary.

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