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Math articles

Explanations and worked examples for math topics. Prefer to just run the numbers? Browse the Math calculators.

Diagram showing an increase from 80 dollars to 100 dollars, a change of 20 dollars equal to a 25 percent increase

How to Calculate Percentage Increase and Decrease (Step by Step)

Learn how to calculate percentage increase and decrease step by step, with clear formulas, worked examples, common mistakes to avoid, and a free calculator.

Math · October 21, 2026 →