-87.73% is the change from 815 to 100
Calculation steps:
[( 100 - 815 ) ÷ 815] x 100 = -87.73%
Formula
Percentage change = [(100 - 815) / 815] x 100
Subtract the new number by the original number
100 - 815 = -715
-715 ÷ 815 = -0.8773006134969326
-0.8773006134969326 x 100 = -87.73%