-90.09% is the change from 817 to 81
Calculation steps:
[( 81 - 817 ) ÷ 817] x 100 = -90.09%
Formula
Percentage change = [(81 - 817) / 817] x 100
Subtract the new number by the original number
81 - 817 = -736
-736 ÷ 817 = -0.9008567931456548
-0.9008567931456548 x 100 = -90.09%