Working back to old price
You learn to work out the old price of an item when you know the discount and the sale price.
How to work it out
- The sale price is less than 100%: after 25% discount you pay 75%.
- Divide the new price by that percentage for 1%, and do times 100 for the old price.
80
40
100
50
A worked example
New price £60 after 25% discount
- Take the discount away from 100%: 100 − 25 = 75.
- The new price of £60 is 75%.
- Divide by 75 and multiply by 100: 60 ÷ 75 × 100 = 80.
- The old price was £80.
More examples
New price £72 after 20% discount
- The new price is 100 − 20 = 80%.
- Work backwards: 72 ÷ 80 × 100 = 90.
- The old price was £90.
New price £45 after 10% discount
- The new price is 90%.
- Work backwards to 100%: 45 ÷ 90 × 100 = 50.
- The old price was £50.
Try it yourself
Calculate back to 100% (the original price)
After 20% discount a coat costs £80. What was the original price?
Calculate back to 100% (the original price)
After 30% discount a coat costs £84. What was the original price?
Watch out
You simply add the discount percentage to the new price.
The discount came off the old price, not the new one. So always work backwards using 1%.
Tips
- First take the discount away from 100%: that percentage is the new price.
- Divide by that percentage and multiply by 100 to find the old price.
Why it works
With a 20% discount, the new price is 80% of the old price. Divide the new price by 80 to find 1%, and multiply by 100 to get the full 100%: the old price.