Three everyday percentage questions, answered as you type.
Most "percentage" questions are one of three things. X% of Y just multiplies — 15% of 80 is 0.15 × 80 = 12. What percent is X of Y divides and scales — 30 out of 120 is 30 ÷ 120 × 100 = 25%. And percent change measures the difference relative to where you started: (new − old) ÷ old × 100, so 50 → 75 is a 50% increase. The change figure is the one people get wrong most often, because the denominator is always the original value, not the new one. For shopping math, the discount calculator and sales tax calculator apply these same formulas to prices.