-21.9% is the change from 831 to 649
Calculation steps:
[( 649 - 831 ) ÷ 831] x 100 = -21.9%
Formula
Percentage change = [(649 - 831) / 831] x 100
Subtract the new number by the original number
649 - 831 = -182
-182 ÷ 831 = -0.2190132370637786
-0.2190132370637786 x 100 = -21.9%