-19.98% is the change from 831 to 665
Calculation steps:
[( 665 - 831 ) ÷ 831] x 100 = -19.98%
Formula
Percentage change = [(665 - 831) / 831] x 100
Subtract the new number by the original number
665 - 831 = -166
-166 ÷ 831 = -0.19975932611311673
-0.19975932611311673 x 100 = -19.98%