-79.78% is the change from 821 to 166
Calculation steps:
[( 166 - 821 ) ÷ 821] x 100 = -79.78%
Formula
Percentage change = [(166 - 821) / 821] x 100
Subtract the new number by the original number
166 - 821 = -655
-655 ÷ 821 = -0.7978075517661388
-0.7978075517661388 x 100 = -79.78%