EAN13 Excel (first 4 digit)

ean13.vb

Function EAN_13(Code As String) As String
    Dim s As String
    s = Code
    cs = 0
    
    For i = 1 To 12
        digit = Mid(s, i, 1) - "0"
        If i Mod 2 = 0 Then
          cs = cs + digit * 3
        Else
            cs = cs + digit * 1
        End If
    Next i

    cs = (10 - (cs Mod 10)) Mod 10
       
    EAN_13 = s & cs
End Function