-80.24% is the change from 840 to 166
Calculation steps:
[( 166 - 840 ) ÷ 840] x 100 = -80.24%
Formula
Percentage change = [(166 - 840) / 840] x 100
Subtract the new number by the original number
166 - 840 = -674
-674 ÷ 840 = -0.8023809523809524
-0.8023809523809524 x 100 = -80.24%