-98.9% is the change from 819 to 9
Calculation steps:
[( 9 - 819 ) ÷ 819] x 100 = -98.9%
Formula
Percentage change = [(9 - 819) / 819] x 100
Subtract the new number by the original number
9 - 819 = -810
-810 ÷ 819 = -0.989010989010989
-0.989010989010989 x 100 = -98.9%