Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    If Target.Address = "$A$1" Then
        Application.ScreenUpdating = False
        Application.EnableEvents = False
        With ActiveSheet
            If Not Target.Font.Bold Then
                MyStr = Empty
                y = 2
                Do
                    F6N = True
                    For x = 1 To 6
                        N6 = Asc(Mid(.Cells(y, 1), x, 1))
                        If N6 < 48 Or N6 > 57 Then F6N = False
                    Next x
                    If F6N Then
                        If MyStr <> Empty Then MyStr = MyStr & ","
                        MyStr = MyStr & .Cells(y, 1)
                    End If
                    y = y + 1
                Loop Until .Cells(y, 1) = Empty
                ary = Split(MyStr, ",")
                If .FilterMode Then .ShowAllData
                .Range("A:A").AutoFilter
                .Range("A:A").AutoFilter Field:=1, Criteria1:=(ary), Operator:=xlFilterValues
            Else
                .Range("A:A").AutoFilter Field:=1
            End If
            Target.Font.Bold = Not Target.Font.Bold
            .Range("B1").Select
        End With
        Application.EnableEvents = True
        Application.ScreenUpdating = True
    End If
End Sub
Private Sub A_F6N()
        Application.ScreenUpdating = False
        Application.EnableEvents = False
        With ActiveSheet
            If Not .Range("A1").Font.Bold Then
                MyStr = Empty
                y = 2
                Do
                    F6N = True
                    For x = 1 To 6
                        N6 = Asc(Mid(.Cells(y, 1), x, 1))
                        If N6 < 48 Or N6 > 57 Then F6N = False
                    Next x
                    If F6N Then
                        If MyStr <> Empty Then MyStr = MyStr & ","
                        MyStr = MyStr & .Cells(y, 1)
                    End If
                    y = y + 1
                Loop Until .Cells(y, 1) = Empty
                ary = Split(MyStr, ",")
                If .FilterMode Then .ShowAllData
                .Range("A:A").AutoFilter
                .Range("A:A").AutoFilter Field:=1, Criteria1:=(ary), Operator:=xlFilterValues
            Else
                .Range("A:A").AutoFilter Field:=1
            End If
            .Range("A1").Font.Bold = Not .Range("A1").Font.Bold
            .Range("B1").Select
        End With
        Application.EnableEvents = True
        Application.ScreenUpdating = True
End Sub