-3.45% is the change from 840 to 811
Calculation steps:
[( 811 - 840 ) ÷ 840] x 100 = -3.45%
Formula
Percentage change = [(811 - 840) / 840] x 100
Subtract the new number by the original number
811 - 840 = -29
-29 ÷ 840 = -0.034523809523809526
-0.034523809523809526 x 100 = -3.45%