-26.69% is the change from 873 to 640
Calculation steps:
[( 640 - 873 ) ÷ 873] x 100 = -26.69%
Formula
Percentage change = [(640 - 873) / 873] x 100
Subtract the new number by the original number
640 - 873 = -233
-233 ÷ 873 = -0.26689576174112256
-0.26689576174112256 x 100 = -26.69%