1500% is the change from 20 to 320
Calculation steps:
[( 320 - 20 ) ÷ 20] x 100 = 1500%
Formula
Percentage change = [(320 - 20) / 20] x 100
Subtract the new number by the original number
320 - 20 = 300
300 ÷ 20 = 15
15 x 100 = 1500%
Example