-98.57% is the change from 840 to 12
Calculation steps:
[( 12 - 840 ) ÷ 840] x 100 = -98.57%
Formula
Percentage change = [(12 - 840) / 840] x 100
Subtract the new number by the original number
12 - 840 = -828
-828 ÷ 840 = -0.9857142857142858
-0.9857142857142858 x 100 = -98.57%