900% is the change from 99 to 990
Calculation steps:
[( 990 - 99 ) ÷ 99] x 100 = 900%
Formula
Percentage change = [(990 - 99) / 99] x 100
Subtract the new number by the original number
990 - 99 = 891
891 ÷ 99 = 9
9 x 100 = 900%
Example