Stacked Discounts Explained
Retailers sometimes run stacked promotions—for example 20% off, then an extra 10% off the reduced price. These do not add to 30% off the original tag.
Sequential formula
After first discount: price₁ = list × (1 − d₁/100)
After second: price₂ = price₁ × (1 − d₂/100)
Combined factor = (1 − d₁/100) × (1 − d₂/100)
Worked example
$100 with 20% then 10% off: $100 × 0.8 = $80, then $80 × 0.9 = $72 (28% total off, not 30%).
Common mistake
Adding percents (20 + 10) overstates savings. Always multiply the remaining-price factors.