-89.54% is the change from 870 to 91
Calculation steps:
[( 91 - 870 ) ÷ 870] x 100 = -89.54%
Formula
Percentage change = [(91 - 870) / 870] x 100
Subtract the new number by the original number
91 - 870 = -779
-779 ÷ 870 = -0.8954022988505748
-0.8954022988505748 x 100 = -89.54%