Percent of Increase and Decrease

Percent of change (increase or decrease) is a mathematical concept that represents the degree of change over time.

To find the percentage of increase or decrease:
 

1. New Number – Original Number
2. (The result ÷ Original Number) × 100

-  Or use this formula: Percent of change =

-  Note: If your answer is a negative number, then this is a percentage decrease. If it is positive, then this is a percentage increase.

Examples:
Example 1.  The price of a shirt increases from to . What is the percentage increase?
Solution: First, find the difference:
Then: . The percentage increase is 20%. It means that the price of the shirt increased by 20%.

Example 2.  The price of a table decreased from to . What is the percent of decrease?
Solution: Use this formula:


.

The percentage decrease is 30. (the negative sign means percentage decrease) Therefore, the price of the table decreased by 30%.