-98.93% is the change from 840 to 9
Calculation steps:
[( 9 - 840 ) ÷ 840] x 100 = -98.93%
Formula
Percentage change = [(9 - 840) / 840] x 100
Subtract the new number by the original number
9 - 840 = -831
-831 ÷ 840 = -0.9892857142857143
-0.9892857142857143 x 100 = -98.93%