-90.42% is the change from 866 to 83
Calculation steps:
[( 83 - 866 ) ÷ 866] x 100 = -90.42%
Formula
Percentage change = [(83 - 866) / 866] x 100
Subtract the new number by the original number
83 - 866 = -783
-783 ÷ 866 = -0.9041570438799076
-0.9041570438799076 x 100 = -90.42%