All XL worksheets have exactly 256 columns (and 65536 rows). You can't
change that.
However, if you enter
D:IV
in the Name box (on the left side of the Formula bar), and choose the
menu item
Format/Column/Hide
only 3 columns will be visible.
This doesn't prevent users from using the name box to select cells in
hidden columns. For that you'd need to restrict the selection. Put this
in your worksheet code module (right-click on the worksheet tab and
choose View Code):
Private Sub Worksheet_SelectionChange(ByVal rSelected As Range)
Dim rSelect As Range
Set rSelect = Intersect(Range("A:C"), rSelected)
If rSelect Is Nothing Then
With rSelected
Set rSelect = Me.Cells(.Item(1).Row, 3).Resize( _
.Rows.Count, 1)
End With
End If
rSelect.Select
End Sub