-18.68% is the change from 819 to 666
Calculation steps:
[( 666 - 819 ) ÷ 819] x 100 = -18.68%
Formula
Percentage change = [(666 - 819) / 819] x 100
Subtract the new number by the original number
666 - 819 = -153
-153 ÷ 819 = -0.18681318681318682
-0.18681318681318682 x 100 = -18.68%