Property: Checksum

AxBarcode1.TypeName = "EAN-13"
AxBarcode1.Text = "431234100707"
MessageBox.Show("The check digit of this code is: " & AxBarcode1.Checksum)

Barcode1.Type_ := 1; // EAN_13
Barcode1.Text := '431234100707';
Application.Messagebox(Pchar(inttostr(Barcode1.Checksum)),
                       'The barcodes check digit',mb_ok);