-89.99% is the change from 809 to 81
Calculation steps:
[( 81 - 809 ) ÷ 809] x 100 = -89.99%
Formula
Percentage change = [(81 - 809) / 809] x 100
Subtract the new number by the original number
81 - 809 = -728
-728 ÷ 809 = -0.899876390605686
-0.899876390605686 x 100 = -89.99%