Breakdown
How it works
25% off then an extra 10% off is not 35% off: 100 × 0.75 × 0.90 = 67.50, a 32.5% effective discount. Retailers rely on shoppers adding the percentages.
Formula
Price after = original × (1 − d₁) × (1 − d₂)
Effective discount = 1 − price after ÷ original
Worked example
120 with 25% off = 90 (save 30). Extra 10% on top = 81, an effective 32.5% discount.
Frequently asked questions
How do I work out a percentage off quickly?
10% is the price with the decimal moved one place; 5% is half that; combine. 25% off 120: 10% = 12, so 20% = 24, 5% = 6 → 30 off.
What is the original price if I know the sale price?
Sale price ÷ (1 − discount). 81 after 32.5% off → 81 ÷ 0.675 = 120.