-26.09% is the change from 870 to 643
Calculation steps:
[( 643 - 870 ) ÷ 870] x 100 = -26.09%
Formula
Percentage change = [(643 - 870) / 870] x 100
Subtract the new number by the original number
643 - 870 = -227
-227 ÷ 870 = -0.26091954022988506
-0.26091954022988506 x 100 = -26.09%