-96.32% is the change from 815 to 30
Calculation steps:
[( 30 - 815 ) ÷ 815] x 100 = -96.32%
Formula
Percentage change = [(30 - 815) / 815] x 100
Subtract the new number by the original number
30 - 815 = -785
-785 ÷ 815 = -0.9631901840490797
-0.9631901840490797 x 100 = -96.32%