-88.62% is the change from 870 to 99
Calculation steps:
[( 99 - 870 ) ÷ 870] x 100 = -88.62%
Formula
Percentage change = [(99 - 870) / 870] x 100
Subtract the new number by the original number
99 - 870 = -771
-771 ÷ 870 = -0.8862068965517241
-0.8862068965517241 x 100 = -88.62%