Sub MySerial()
    Dim rngSerialLocation As Range
    Dim intSerialNum As Integer
    Dim strSerialNum As String
    Dim docCurrent As Document
    Dim intNumCopies As Integer
    Dim intCount As Integer

    ' set ref to current active doc
    Set docCurrent = Application.ActiveDocument
    ' set ref to the bookmarked serial number
    Set rngSerialLocation = docCurrent.Bookmarks("Serial").Range

    ' get the starting number
    intSerialNum = Val(rngSerialLocation.Text)
    ' get the number of copies required
    intNumCopies = Val(InputBox$("How many Copies?", _
      "Print Serialized", "1"))

    For intCount = 1 To intNumCopies
        ' print the document
        docCurrent.PrintOut Range:=wdPrintAllDocument
        ' increment the serial number
        intSerialNum = intSerialNum + 1
        ' put into formatted version
        strSerialNum = Format(intSerialNum, "00000")
        ' stuff into proper place
        rngSerialLocation.Text = strSerialNum
    Next intCount

    ' reset the bookmark, since the updating procedure
    ' wipes out the old one
    docCurrent.Bookmarks.Add Name:="Serial", _
      Range:=rngSerialLocation
End Sub