-20.84% is the change from 811 to 642
Calculation steps:
[( 642 - 811 ) ÷ 811] x 100 = -20.84%
Formula
Percentage change = [(642 - 811) / 811] x 100
Subtract the new number by the original number
642 - 811 = -169
-169 ÷ 811 = -0.20838471023427868
-0.20838471023427868 x 100 = -20.84%