4050% is the change from 20 to 830
Calculation steps:
[( 830 - 20 ) ÷ 20] x 100 = 4050%
Formula
Percentage change = [(830 - 20) / 20] x 100
Subtract the new number by the original number
830 - 20 = 810
810 ÷ 20 = 40.5
40.5 x 100 = 4050%
Example