-80.63% is the change from 857 to 166
Calculation steps:
[( 166 - 857 ) ÷ 857] x 100 = -80.63%
Formula
Percentage change = [(166 - 857) / 857] x 100
Subtract the new number by the original number
166 - 857 = -691
-691 ÷ 857 = -0.8063010501750292
-0.8063010501750292 x 100 = -80.63%