-79.76% is the change from 820 to 166
Calculation steps:
[( 166 - 820 ) ÷ 820] x 100 = -79.76%
Formula
Percentage change = [(166 - 820) / 820] x 100
Subtract the new number by the original number
166 - 820 = -654
-654 ÷ 820 = -0.7975609756097561
-0.7975609756097561 x 100 = -79.76%