Hello Bruce,

Only a few changes were needed to make your macro work the way you wanted. Here it is...

Public Sub Add2()

 Dim Cell
 Dim CellRange As Range
 
  Set CellRange = Selection
  
   For Each Cell In CellRange
    If Len(Cell.Value) = 7 Then
      junk = "00" & Cell.Value
    Else
      junk = "0" & Cell.Value
    End If
    Range(Cell.Address).Value = junk
   Next Cell

End Sub