-81.2% is the change from 830 to 156
Calculation steps:
[( 156 - 830 ) ÷ 830] x 100 = -81.2%
Formula
Percentage change = [(156 - 830) / 830] x 100
Subtract the new number by the original number
156 - 830 = -674
-674 ÷ 830 = -0.8120481927710843
-0.8120481927710843 x 100 = -81.2%