-79.63% is the change from 815 to 166
Calculation steps:
[( 166 - 815 ) ÷ 815] x 100 = -79.63%
Formula
Percentage change = [(166 - 815) / 815] x 100
Subtract the new number by the original number
166 - 815 = -649
-649 ÷ 815 = -0.7963190184049079
-0.7963190184049079 x 100 = -79.63%