800% is the change from 10 to 90
Calculation steps:
[( 90 - 10 ) ÷ 10] x 100 = 800%
Formula
Percentage change = [(90 - 10) / 10] x 100
Subtract the new number by the original number
90 - 10 = 80
80 ÷ 10 = 8
8 x 100 = 800%
Example