-89.99% is the change from 909 to 91
Calculation steps:
[( 91 - 909 ) ÷ 909] x 100 = -89.99%
Formula
Percentage change = [(91 - 909) / 909] x 100
Subtract the new number by the original number
91 - 909 = -818
-818 ÷ 909 = -0.8998899889988999
-0.8998899889988999 x 100 = -89.99%