-89.64% is the change from 830 to 86
Calculation steps:
[( 86 - 830 ) ÷ 830] x 100 = -89.64%
Formula
Percentage change = [(86 - 830) / 830] x 100
Subtract the new number by the original number
86 - 830 = -744
-744 ÷ 830 = -0.8963855421686747
-0.8963855421686747 x 100 = -89.64%