-90.7% is the change from 871 to 81
Calculation steps:
[( 81 - 871 ) ÷ 871] x 100 = -90.7%
Formula
Percentage change = [(81 - 871) / 871] x 100
Subtract the new number by the original number
81 - 871 = -790
-790 ÷ 871 = -0.9070034443168772
-0.9070034443168772 x 100 = -90.7%