Reverse percentages

Using reverse percentages is a way of working backwards on a percentages problem in order to find the original amount.

In order to do this, we:

  1. Either add/subtract the percentage given in the problem from 100% to determine what percentage we have
  2. Find 1% by dividing by percentage found in previous step
  3. Find 100% (original amount) by multiplying your answer in step 2 by 100

For example, if you have to work out the original price of a laptop that is being sold at 25% off:

  1. work out the current price as a percentage of the original price (100%): current price is 100% - 25%
  2. Find 1% by dividing the current price by 75
  3. Multiply this 1% by 100 to find the original price (100%)