Sub PrintJobs()
Dim i As Long, startnum As Long, lastnum As Long
Dim orng As Range
    Set orng = ActiveDocument.SelectContentControlsByTitle("Serialnumber").Item(1).Range
    startnum = InputBox("Enter the first job number to be printed", "Print Job Number", 1)
    lastnum = InputBox("Enter the last job number to be printed", "Print Job Number", 1)
    For i = startnum To lastnum
        orng.Text = Format(Date, "mmyy") & Format(i, "00")
        ActiveDocument.PrintOut
    Next
    Set orng = Nothing
End Sub