-90.63% is the change from 864 to 81
Calculation steps:
[( 81 - 864 ) ÷ 864] x 100 = -90.63%
Formula
Percentage change = [(81 - 864) / 864] x 100
Subtract the new number by the original number
81 - 864 = -783
-783 ÷ 864 = -0.90625
-0.90625 x 100 = -90.63%