3975% is the change from 20 to 815
Calculation steps:
[( 815 - 20 ) ÷ 20] x 100 = 3975%
Formula
Percentage change = [(815 - 20) / 20] x 100
Subtract the new number by the original number
815 - 20 = 795
795 ÷ 20 = 39.75
39.75 x 100 = 3975%
Example