-26.9% is the change from 870 to 636
Calculation steps:
[( 636 - 870 ) ÷ 870] x 100 = -26.9%
Formula
Percentage change = [(636 - 870) / 870] x 100
Subtract the new number by the original number
636 - 870 = -234
-234 ÷ 870 = -0.2689655172413793
-0.2689655172413793 x 100 = -26.9%