-26.88% is the change from 878 to 642
Calculation steps:
[( 642 - 878 ) ÷ 878] x 100 = -26.88%
Formula
Percentage change = [(642 - 878) / 878] x 100
Subtract the new number by the original number
642 - 878 = -236
-236 ÷ 878 = -0.26879271070615035
-0.26879271070615035 x 100 = -26.88%