Year 8: Percentage change

This cheat-sheet helps you calculate percentage changes in numbers. A percentage change tells you how much a number has increased or decreased compared to its original value.

Formula

The formula to calculate percentage change is:

Percentage Change = (New Value - Old Value) / Old Value * 100

Types of change

Percentage increase

If the result is positive, it’s a percentage increase. This means the new value is higher than the old value.

Percentage decrease

If the result is negative, it’s a percentage decrease. This means the new value is lower than the old value.

Example

Example: Original Value = $50, New Value = $60

Percentage Change = $(60-50)/50\times 100$

= $(10/50)\times 100$

= $0.2\times 100$

= 20% Increase

Another example: Original Value = $80, New Value = $60

Percentage Change = $(60-80)/80\times 100$

= $(-20/80)\times 100$

= $-0.25\times 100$

= 25% Decrease

Remember to always state whether it’s an increase or a decrease.