2000% is the change from 20 to 420
Calculation steps:
[( 420 - 20 ) ÷ 20] x 100 = 2000%
Formula
Percentage change = [(420 - 20) / 20] x 100
Subtract the new number by the original number
420 - 20 = 400
400 ÷ 20 = 20
20 x 100 = 2000%
Example