-79.3% is the change from 831 to 172
Calculation steps:
[( 172 - 831 ) ÷ 831] x 100 = -79.3%
Formula
Percentage change = [(172 - 831) / 831] x 100
Subtract the new number by the original number
172 - 831 = -659
-659 ÷ 831 = -0.7930204572803851
-0.7930204572803851 x 100 = -79.3%