-79.52% is the change from 840 to 172
Calculation steps:
[( 172 - 840 ) ÷ 840] x 100 = -79.52%
Formula
Percentage change = [(172 - 840) / 840] x 100
Subtract the new number by the original number
172 - 840 = -668
-668 ÷ 840 = -0.7952380952380952
-0.7952380952380952 x 100 = -79.52%