3990% is the change from 20 to 818
Calculation steps:
[( 818 - 20 ) ÷ 20] x 100 = 3990%
Formula
Percentage change = [(818 - 20) / 20] x 100
Subtract the new number by the original number
818 - 20 = 798
798 ÷ 20 = 39.9
39.9 x 100 = 3990%
Example