-99.37% is the change from 638 to 4
Calculation steps:
[( 4 - 638 ) ÷ 638] x 100 = -99.37%
Formula
Percentage change = [(4 - 638) / 638] x 100
Subtract the new number by the original number
4 - 638 = -634
-634 ÷ 638 = -0.9937304075235109
-0.9937304075235109 x 100 = -99.37%