Private Sub CommandButton1_Click()
Dim origL, origC As Integer
origL = ActiveWindow.RangeSelection.Row
origC = ActiveWindow.RangeSelection.Column
If ActiveWindow.RangeSelection.Columns.Count <> 4 Then
MsgBox 'Sélection Incorrecte : veuillez selectionner une zone sur 4 colonnes'
Exit Sub
End If
For i = origL To (origL + ActiveWindow.RangeSelection.Rows.Count - 1)
Cells(i, origC + 3).Select
ActiveCell.Value = ActiveCell.Offset(0, -3).Value + ActiveCell.Offset(0, -1).Value
Next i
End Sub