-20.33% is the change from 836 to 666
Calculation steps:
[( 666 - 836 ) ÷ 836] x 100 = -20.33%
Formula
Percentage change = [(666 - 836) / 836] x 100
Subtract the new number by the original number
666 - 836 = -170
-170 ÷ 836 = -0.20334928229665072
-0.20334928229665072 x 100 = -20.33%