-79.02% is the change from 815 to 171
Calculation steps:
[( 171 - 815 ) ÷ 815] x 100 = -79.02%
Formula
Percentage change = [(171 - 815) / 815] x 100
Subtract the new number by the original number
171 - 815 = -644
-644 ÷ 815 = -0.7901840490797546
-0.7901840490797546 x 100 = -79.02%