-1.22% is the change from 821 to 811
Calculation steps:
[( 811 - 821 ) ÷ 821] x 100 = -1.22%
Formula
Percentage change = [(811 - 821) / 821] x 100
Subtract the new number by the original number
811 - 821 = -10
-10 ÷ 821 = -0.012180267965895249
-0.012180267965895249 x 100 = -1.22%