There are a number of ways in which percentages can be calculated. In this section will talk about the "multiplication" or "multiplier" method which is a two-stage process for calculating percentage increase or percentage decrease.


  • Convert the percentage value that is going to be used to a decimal, then either add to or subtract from one, depending on whether you're looking at a percentage increase, or percentage decrease.
  • Use your newly created multiplier on the value which you wish to increase or decrease, and this will give you your answer.


Examples:


Q. Calculate the new value of a pair of shoes priced at £45 once VAT at 20% has been applied.


A. 20% as a decimal number is 0.2, add this to 1, making a multiplier of 1.2, we then multiply 1.2 by 45 to arrive at an answer.



Q . Calculate the sale price of a pair of trousers, originally priced at £35 if they are reduced in a sale by 30%.


A. First of all we convert 30% to a decimal which is 0.3, and this time we subtract it from one because we are performing a reduction. This gives us a multiplier of 0.7 which with then apply to the original price :



We can now see that the new price of the trousers after the reduction would be £24.50.