-99.2% is the change from 870 to 7
Calculation steps:
[( 7 - 870 ) ÷ 870] x 100 = -99.2%
Formula
Percentage change = [(7 - 870) / 870] x 100
Subtract the new number by the original number
7 - 870 = -863
-863 ÷ 870 = -0.9919540229885058
-0.9919540229885058 x 100 = -99.2%