-98.59% is the change from 638 to 9
Calculation steps:
[( 9 - 638 ) ÷ 638] x 100 = -98.59%
Formula
Percentage change = [(9 - 638) / 638] x 100
Subtract the new number by the original number
9 - 638 = -629
-629 ÷ 638 = -0.9858934169278997
-0.9858934169278997 x 100 = -98.59%