-98.28% is the change from 870 to 15
Calculation steps:
[( 15 - 870 ) ÷ 870] x 100 = -98.28%
Formula
Percentage change = [(15 - 870) / 870] x 100
Subtract the new number by the original number
15 - 870 = -855
-855 ÷ 870 = -0.9827586206896551
-0.9827586206896551 x 100 = -98.28%