Private Sub Worksheet_Change(ByVal Target As Excel.Range)
      With Target
         If .Address(False, False) = "М10" Then
            If IsNumeric(.Value) Then
               Application.EnableEvents = False
               Range("A2").Value = Range("М12").Value + .Value
               Application.EnableEvents = True
            End If
         End If
      End With
End Sub

Private Sub Worksheet_Change(ByVal Target As Excel.Range)
    With Target
        If .Cells.Count >  1  Then Exit Sub
        If Intersect(.Cells, Range("Name1")) Is Nothing Then Exit Sub
        If Not IsNumeric(.Value) Then Exit Sub
        Application.EnableEvents = False
        Range("Name2") = Range("Name3") + .Value
        Application.EnableEvents = True
    End With
End Sub