-39.59% is the change from 831 to 502
Calculation steps:
[( 502 - 831 ) ÷ 831] x 100 = -39.59%
Formula
Percentage change = [(502 - 831) / 831] x 100
Subtract the new number by the original number
502 - 831 = -329
-329 ÷ 831 = -0.39590854392298436
-0.39590854392298436 x 100 = -39.59%