-87.95% is the change from 830 to 100
Calculation steps:
[( 100 - 830 ) ÷ 830] x 100 = -87.95%
Formula
Percentage change = [(100 - 830) / 830] x 100
Subtract the new number by the original number
100 - 830 = -730
-730 ÷ 830 = -0.8795180722891566
-0.8795180722891566 x 100 = -87.95%