-96.55% is the change from 870 to 30
Calculation steps:
[( 30 - 870 ) ÷ 870] x 100 = -96.55%
Formula
Percentage change = [(30 - 870) / 870] x 100
Subtract the new number by the original number
30 - 870 = -840
-840 ÷ 870 = -0.9655172413793104
-0.9655172413793104 x 100 = -96.55%