3900% is the change from 1 to 40
Calculation steps:
[( 40 - 1 ) ÷ 1] x 100 = 3900%
Formula
Percentage change = [(40 - 1) / 1] x 100
Subtract the new number by the original number
40 - 1 = 39
39 ÷ 1 = 39
39 x 100 = 3900%
Example