Percentage Calculator

A percentage expresses a number as a fraction of 100. The % symbol means 'per hundred' and is one of the most commonly used concepts in daily life — from store discounts and tax rates to statistics and school grades. Three core percentage calculations: (1) What is X% of Y? — multiply Y by X/100. (2) X is what percent of Y? — divide X by Y, then multiply by 100. (3) Percentage change — subtract old value from new, divide by old, multiply by 100. Common uses: Sales discounts (30% off), tip calculation (15% tip on a restaurant bill), tax rates (VAT/sales tax), grade scores (scored 85/100 = 85%), interest rates on loans and savings, and statistical data interpretation. Percentage increase vs. decrease: A 50% increase followed by a 50% decrease does NOT bring you back to the original value. If you start with 100, increase by 50% = 150, then decrease by 50% = 75. This asymmetry is important to understand in finance and investments.