-81.12% is the change from 821 to 155
Calculation steps:
[( 155 - 821 ) ÷ 821] x 100 = -81.12%
Formula
Percentage change = [(155 - 821) / 821] x 100
Subtract the new number by the original number
155 - 821 = -666
-666 ÷ 821 = -0.8112058465286236
-0.8112058465286236 x 100 = -81.12%