-99.69% is the change from 638 to 2
Calculation steps:
[( 2 - 638 ) ÷ 638] x 100 = -99.69%
Formula
Percentage change = [(2 - 638) / 638] x 100
Subtract the new number by the original number
2 - 638 = -636
-636 ÷ 638 = -0.9968652037617555
-0.9968652037617555 x 100 = -99.69%