3750% is the change from 20 to 770
Calculation steps:
[( 770 - 20 ) ÷ 20] x 100 = 3750%
Formula
Percentage change = [(770 - 20) / 20] x 100
Subtract the new number by the original number
770 - 20 = 750
750 ÷ 20 = 37.5
37.5 x 100 = 3750%
Example