990% is the change from 10 to 109
Calculation steps:
[( 109 - 10 ) ÷ 10] x 100 = 990%
Formula
Percentage change = [(109 - 10) / 10] x 100
Subtract the new number by the original number
109 - 10 = 99
99 ÷ 10 = 9.9
9.9 x 100 = 990%
Example