-99.15% is the change from 820 to 7
Calculation steps:
[( 7 - 820 ) ÷ 820] x 100 = -99.15%
Formula
Percentage change = [(7 - 820) / 820] x 100
Subtract the new number by the original number
7 - 820 = -813
-813 ÷ 820 = -0.9914634146341463
-0.9914634146341463 x 100 = -99.15%