-4.33% is the change from 878 to 840
Calculation steps:
[( 840 - 878 ) ÷ 878] x 100 = -4.33%
Formula
Percentage change = [(840 - 878) / 878] x 100
Subtract the new number by the original number
840 - 878 = -38
-38 ÷ 878 = -0.04328018223234624
-0.04328018223234624 x 100 = -4.33%