Calculation GuideVerified Formula

How to calculate a percentage

Turn a part and a whole into a percentage, and convert a percentage back into a value.

1The core formula

Percentage = (part ÷ whole) × 100. If 42 students passed out of 50, the pass rate is (42 ÷ 50) × 100 = 84%. Reverse the formula when you know the percentage and need the original whole: original = known × 100 ÷ percentage.

2Increases and discounts

A percentage increase multiplies by (1 + r/100). Sequential discounts do not add. 10% then 5% is 0.90 × 0.95 = 0.855, an effective 14.5% reduction, not 15%.

Try It Yourself With Interactive Calculators

Put these formulas into action right in your browser:

Percentage Calculator

Find what percent one number is of another.

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Reverse Percentage

Recover the original whole from a known percentage amount.

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Discount Calculator

Apply one or several sequential discounts to a price.

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Guide Quick Overview

Category: Educational reference

Verified: Accurate mathematical algorithms with boundary validation.

Sections: 2 core learning steps.

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