-99.4% is the change from 840 to 5
Calculation steps:
[( 5 - 840 ) ÷ 840] x 100 = -99.4%
Formula
Percentage change = [(5 - 840) / 840] x 100
Subtract the new number by the original number
5 - 840 = -835
-835 ÷ 840 = -0.9940476190476191
-0.9940476190476191 x 100 = -99.4%