-24.02% is the change from 870 to 661
Calculation steps:
[( 661 - 870 ) ÷ 870] x 100 = -24.02%
Formula
Percentage change = [(661 - 870) / 870] x 100
Subtract the new number by the original number
661 - 870 = -209
-209 ÷ 870 = -0.24022988505747125
-0.24022988505747125 x 100 = -24.02%