Reverse Percentages

The main formula that you need to remember for reverse percentages is...
1. original amount x multiplier = current amount
How to know what to put as the multiplier
1. If the word "increased" is used, you needed to add the number to 1.
  1. A radio sells for £63, after a 40% increase in the cost price.
    1. The multiplier of 40 is 1.4.
      1. 1 + 0.4 = 1.4
      2. 63 / 1.4 = 45
        Original amount was £45
2. If the word "decreased" or "reduced" is used, you need to subtract the number from 1.
  1. I brought a jacket, which was in a sale, and after being reduced by 20%, it cost £15. What was the original price?
    1. The multiplier of 20 is 0.8.
      1. 1 - 0.2= 0.8
      2. 15 / 0.8 = £18.75
        Original amount was £45.
If you can remember that if it is increased you add it to 1 and if it is dereased then you subtract it from 1, then you will do fine when the question comes up about it.
Try the first 4 questions in this test.
1. www.bbc.co.uk/bitesize/quiz/q29288021

Resource summary

	Created by Olivia Dawkins over 6 years ago