-88.21% is the change from 840 to 99
Calculation steps:
[( 99 - 840 ) ÷ 840] x 100 = -88.21%
Formula
Percentage change = [(99 - 840) / 840] x 100
Subtract the new number by the original number
99 - 840 = -741
-741 ÷ 840 = -0.8821428571428571
-0.8821428571428571 x 100 = -88.21%