-20.46% is the change from 831 to 661
Calculation steps:
[( 661 - 831 ) ÷ 831] x 100 = -20.46%
Formula
Percentage change = [(661 - 831) / 831] x 100
Subtract the new number by the original number
661 - 831 = -170
-170 ÷ 831 = -0.2045728038507822
-0.2045728038507822 x 100 = -20.46%