The original value before the 20% decrease was 100.
Show calculation steps
- Remaining multiplier = 1 − 0.2 = 0.8.
- Divide 80 by the multiplier = 100.
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Recover a jacket’s original price
Sale price: 80 · Discount: 20%
- 01
A 20% discount leaves 80%, or 0.8, of the original.
- 02
Divide the sale price by 0.8: 80 ÷ 0.8 = 100.
Illustrative example · Adding 20% to 80 gives 96, not the original price. A 100% discount cannot be reversed uniquely.
Load this example ↗Formula & method
Reverse percentages are useful when you know the final number but need to reconstruct the starting number. The correct operation is division by the percentage multiplier, not simply adding the percentage back.
Frequently asked questions
Why can't I just add 20% back after a 20% discount?
Because the 20% discount was based on the larger original value. Adding 20% to the smaller final value uses a different base.
Can I reverse a 100% decrease?
No. Once the final value is zero after a 100% decrease, the original cannot be uniquely recovered from that information alone.