-98.2% is the change from 835 to 15
Calculation steps:
[( 15 - 835 ) ÷ 835] x 100 = -98.2%
Formula
Percentage change = [(15 - 835) / 835] x 100
Subtract the new number by the original number
15 - 835 = -820
-820 ÷ 835 = -0.9820359281437125
-0.9820359281437125 x 100 = -98.2%