Percentage Increase and Decrease

What is percentage increase and decrease? 

This is when we increase a value by a percentage by adding, or decrease a value by a percentage by subtracting. 

To do this we use a multiplier:

e.g. Increase by 30% = x 1.3     <--------------------------     100% + 30% = 130%

       Decrease by 30% = x 0.7   <---------------------------    100% - 30% = 70%

For example: Katie earns £40 per week for her part-time job. She is to be given a 5% pay rise. How much will she earn per week after the pay rise?

£40 x 1.05 = £42

For example: In a sale the cost of a computer is reduced by 30%. The normal price of the computer was £900. Calculate the sale price of the computer.

£900 x 0.7 = £630

Always check your answer by doing the inverse of the calculation. 

Practise these exam style questions to improve your knowledge and understanding.

Decrease the following:

a) £730.25 by 43%     b) £0.57 by 23%     c) 18kg by 60%     d) 134ml by 2.5%

A small firm employs 3 staff. They are all given a 4% pay rise. Calculate the new salary for each member of staff.

The original salaries are as follows:

Jedadiah Harinbown     £24 000

Alice Holland                      £22 500

Graham Hall                 £14 000

Omar Lynch                 £19 250

Sammi Lotus                £21 000