9900% is the change from 8 to 800
Calculation steps:
[( 800 - 8 ) ÷ 8] x 100 = 9900%
Formula
Percentage change = [(800 - 8) / 8] x 100
Subtract the new number by the original number
800 - 8 = 792
792 ÷ 8 = 99
99 x 100 = 9900%
Example