-98.66% is the change from 671 to 9
Calculation steps:
[( 9 - 671 ) ÷ 671] x 100 = -98.66%
Formula
Percentage change = [(9 - 671) / 671] x 100
Subtract the new number by the original number
9 - 671 = -662
-662 ÷ 671 = -0.9865871833084948
-0.9865871833084948 x 100 = -98.66%