1. Reverse Percentages
Reverse percentages make it easier to determine an item's original cost or worth after it has increased or dropped in value, for as after a price hike or a sale.
1.1 How to calculate Reverse Percentages?
In order to calculate Reverse Percentages, we use the following methods:
Method 1: Reverse Percentages 1% to 100%
- Write the amount in the question as a percentage of the original value i.e. write an increase of 20% as 120% and a decrease of 10% as 90%
- Divide the amount by this value to find 1% of the original value.
- Multiply by 100.
Example: Sarah buys a top in a sale. It is reduced by 20% down to a price of £40. Work out the original price of the dress.
Solution:
Method 2: Reverse Percentages using decimals
- Write the amount in the question as a percentage of the original value o i.e. write an increase of 20% as 120% and a decrease of 10% as 90%
- Convert this percentage to a decimal or a fraction.
- Divide the amount by this value to find the original value.
Example: Sarah also buys a skirt in the sale. It is reduced by 40% down to a price of £36. Work out the original price of the skirt.
Solution:
Example: 150% of a number is 690. Calculate the original number.
Solution:
