-82.1% is the change from 866 to 155
Calculation steps:
[( 155 - 866 ) ÷ 866] x 100 = -82.1%
Formula
Percentage change = [(155 - 866) / 866] x 100
Subtract the new number by the original number
155 - 866 = -711
-711 ÷ 866 = -0.8210161662817552
-0.8210161662817552 x 100 = -82.1%