-18.81% is the change from 638 to 518
Calculation steps:
[( 518 - 638 ) ÷ 638] x 100 = -18.81%
Formula
Percentage change = [(518 - 638) / 638] x 100
Subtract the new number by the original number
518 - 638 = -120
-120 ÷ 638 = -0.18808777429467086
-0.18808777429467086 x 100 = -18.81%