-1.1% is the change from 820 to 811
Calculation steps:
[( 811 - 820 ) ÷ 820] x 100 = -1.1%
Formula
Percentage change = [(811 - 820) / 820] x 100
Subtract the new number by the original number
811 - 820 = -9
-9 ÷ 820 = -0.01097560975609756
-0.01097560975609756 x 100 = -1.1%