9900% is the change from 1 to 100
Calculation steps:
[( 100 - 1 ) ÷ 1] x 100 = 9900%
Formula
Percentage change = [(100 - 1) / 1] x 100
Subtract the new number by the original number
100 - 1 = 99
99 ÷ 1 = 99
99 x 100 = 9900%
Example