-90.07% is the change from 866 to 86
Calculation steps:
[( 86 - 866 ) ÷ 866] x 100 = -90.07%
Formula
Percentage change = [(86 - 866) / 866] x 100
Subtract the new number by the original number
86 - 866 = -780
-780 ÷ 866 = -0.9006928406466512
-0.9006928406466512 x 100 = -90.07%