-79% is the change from 819 to 172
Calculation steps:
[( 172 - 819 ) ÷ 819] x 100 = -79%
Formula
Percentage change = [(172 - 819) / 819] x 100
Subtract the new number by the original number
172 - 819 = -647
-647 ÷ 819 = -0.78998778998779
-0.78998778998779 x 100 = -79%