guardar un numero y mostrarlo de nuevo programa calculadora

el problema es el siguiente debo hacer uan calculadora cientifica en visual basic
ya tengo casi todas las funciones pero no logro hacer bien las siguientes si alguien me ayude o explique

MS, M-, M+ MR

un ejemplo seria asi
supongamos ingreso el numero 9. le doy el boton C. se borra el contenido e la pantalla, y al pulsar MR deberia volver a mostrar el 9

Código

 
Public Class Form1
    Dim b As Integer
    Dim c As Integer
    Dim num1 As Double
    Dim num2 As Double
    Dim resul As Integer
 
 
 
 
 
 
 
 
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles B1.Click
 
        Tpantalla.Text = Tpantalla.Text & "1"
 
    End Sub
 
    Private Sub Button8_Click(sender As Object, e As EventArgs) Handles Bsuma.Click
 
 
        b = 1
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
 
    End Sub
 
    Private Sub B0_Click(sender As Object, e As EventArgs) Handles B0.Click
 
        Tpantalla.Text = Tpantalla.Text & "0"
    End Sub
 
    Private Sub B2_Click(sender As Object, e As EventArgs) Handles B2.Click
 
        Tpantalla.Text = Tpantalla.Text & "2"
    End Sub
 
    Private Sub B3_Click(sender As Object, e As EventArgs) Handles B3.Click
 
        Tpantalla.Text = Tpantalla.Text & "3"
    End Sub
 
    Private Sub B4_Click(sender As Object, e As EventArgs) Handles B4.Click
        Tpantalla.Text = Tpantalla.Text & "4"
    End Sub
 
    Private Sub B5_Click(sender As Object, e As EventArgs) Handles B5.Click
 
        Tpantalla.Text = Tpantalla.Text & "5"
    End Sub
 
    Private Sub B6_Click(sender As Object, e As EventArgs) Handles B6.Click
 
        Tpantalla.Text = Tpantalla.Text & "6"
    End Sub
 
    Private Sub B7_Click(sender As Object, e As EventArgs) Handles B7.Click
 
        Tpantalla.Text = Tpantalla.Text & "7"
    End Sub
 
    Private Sub B8_Click(sender As Object, e As EventArgs) Handles B8.Click
 
        Tpantalla.Text = Tpantalla.Text & "8"
    End Sub
 
    Private Sub B9_Click(sender As Object, e As EventArgs) Handles B9.Click
 
        Tpantalla.Text = Tpantalla.Text & "9"
    End Sub
 
    Private Sub Bigual_Click(sender As Object, e As EventArgs) Handles Bigual.Click
        num2 = Tpantalla.Text
        If b = 1 Then
            Tpantalla.Text = num1 + num2
 
        End If
        If b = 2 Then
            Tpantalla.Text = num1 - num2
 
        End If
        If b = 3 Then
            Tpantalla.Text = num1 * num2
 
        End If
        If b = 4 Then
            If num2 <> 0 Then
                Tpantalla.Text = num1 / num2
            Else
                Tpantalla.Text = "No divisible"
 
            End If
 
 
 
 
        End If
        If b = 5 Then
            Tpantalla.Text = num1 ^ num2
 
        End If
 
 
    End Sub
 
    Private Sub Bresta_Click(sender As Object, e As EventArgs) Handles Bresta.Click
        b = 2
        Bcoma.Enabled = True
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
    End Sub
 
    Private Sub Bmulti_Click(sender As Object, e As EventArgs) Handles Bmulti.Click
        b = 3
        Bcoma.Enabled = True
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
    End Sub
 
    Private Sub Bdivi_Click(sender As Object, e As EventArgs) Handles Bdivi.Click
        b = 4
        Bcoma.Enabled = True
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
    End Sub
 
    Private Sub Blim_Click(sender As Object, e As EventArgs) Handles Blim.Click
        Tpantalla.Text = ""
        Bcoma.Enabled = True
    End Sub
 
    Private Sub Bcoma_Click(sender As Object, e As EventArgs) Handles Bcoma.Click
 
 
        Tpantalla.Text = Tpantalla.Text & ","
        Bcoma.Enabled = False
 
 
    End Sub
 
    Private Sub Tpantalla_TextChanged(sender As Object, e As EventArgs) Handles Tpantalla.TextChanged
 
    End Sub
 
    Private Sub Buno_Click(sender As Object, e As EventArgs) Handles Buno.Click
 
        Try
 
            Dim lar As Integer
            If Tpantalla.Text <> "" Then
                lar = Tpantalla.Text.Length
                Tpantalla.Text = Mid(Tpantalla.Text, 1, lar - 1)
            End If
        Catch ex As Exception
 
 
 
        End Try
    End Sub
 
    Private Sub Bx_Click(sender As Object, e As EventArgs) Handles Bx.Click
 
        b = 5
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
 
        If b = 5 Then
            Tpantalla.Text = num1 ^ 2
 
        End If
 
 
    End Sub
 
    Private Sub Button7_Click(sender As Object, e As EventArgs) Handles Button7.Click
        b = 5
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
 
 
    End Sub
 
    Private Sub Braiz_Click(sender As Object, e As EventArgs) Handles Braiz.Click
        b = 7
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
 
        If b = 7 Then
            Tpantalla.Text = Math.Sqrt(num1)
 
        End If
    End Sub
 
    Private Sub Button6_Click(sender As Object, e As EventArgs) Handles Button6.Click
        b = 8
        num2 = Tpantalla.Text
        Tpantalla.Text = ""
 
        If b = 8 Then
            Tpantalla.Text = 1 / num2
 
        End If
    End Sub
 
    Private Sub Bmm_Click(sender As Object, e As EventArgs) Handles Bmm.Click
        b = 9
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
 
        If b = 9 Then
            Tpantalla.Text = num1 * (-1)
 
        End If
 
    End Sub
 
    Private Sub Bfac_Click(sender As Object, e As EventArgs) Handles Bfac.Click
        Dim a, b, c As Integer
 
        a = (Tpantalla.Text)
        b = 1
        For c = 1 To a
            b = b * c
            Tpantalla.Text = (b)
        Next
    End Sub
 
    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs)
 
    End Sub
 
    Private Sub Bsen_Click(sender As Object, e As EventArgs) Handles Bsen.Click
 
 
        b = 10
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
 
        If b = 10 Then
            Tpantalla.Text = Math.Sin(Val(num1) * Math.PI / 180)
        End If
    End Sub
 
    Private Sub Bcos_Click(sender As Object, e As EventArgs) Handles Bcos.Click
        b = 11
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
 
        If b = 11 Then
            Tpantalla.Text = Math.Cos(Val(num1) * Math.PI / 180)
        End If
    End Sub
 
    Private Sub Btan_Click(sender As Object, e As EventArgs) Handles Btan.Click
        b = 12
        num1 = Tpantalla.Text
        Tpantalla.Text = ""
 
        If b = 12 Then
            Tpantalla.Text = Math.Tan(Val(num1) * Math.PI / 180)
        End If
    End Sub
 
    Private Sub Bmem_Click(sender As Object, e As EventArgs) Handles Bmem.Click
 
    End Sub
End Class

' El formato del separador de decimales.
Private ReadOnly numberFormat As NumberFormatInfo = CultureInfo.GetCultureInfo("en-US").NumberFormat
Private memValue As Decimal
' M+
Private Sub Button_MemAdd_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles Button_MemAdd.Click
Me.memValue += Decimal.Parse(Me.TextBox_CalcDisplay.Text, Me.numberFormat)
End Sub
' M-
Private Sub Button_MemSubstract_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles Button_MemSubstract.Click
Me.memValue -= Decimal.Parse(Me.TextBox_CalcDisplay.Text, Me.numberFormat)
End Sub
' MR
Private Sub Button_MemRecall_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles Button_MemRecall.Click
Me.TextBox_Input.Text = Convert.ToString(If(Me.memValue = 0.0D, 0D, Me.memValue), Me.numberFormat)
End Sub
' MC
Private Sub Button_MemClear_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles Button_MemClear.Click
Me.memValue = 0D
End Sub

Private Sub B0_Click(sender As Object, e As EventArgs) Handles B0.Click
Tpantalla.Text = Tpantalla.Text & "0"
End Sub
Private Sub B2_Click(sender As Object, e As EventArgs) Handles B2.Click
Tpantalla.Text = Tpantalla.Text & "2"
End Sub
Private Sub B3_Click(sender As Object, e As EventArgs) Handles B3.Click
Tpantalla.Text = Tpantalla.Text & "3"
End Sub
Private Sub B4_Click(sender As Object, e As EventArgs) Handles B4.Click
Tpantalla.Text = Tpantalla.Text & "4"
End Sub
Private Sub B5_Click(sender As Object, e As EventArgs) Handles B5.Click
Tpantalla.Text = Tpantalla.Text & "5"
End Sub
Private Sub B6_Click(sender As Object, e As EventArgs) Handles B6.Click
Tpantalla.Text = Tpantalla.Text & "6"
End Sub
Private Sub B7_Click(sender As Object, e As EventArgs) Handles B7.Click
Tpantalla.Text = Tpantalla.Text & "7"
End Sub
Private Sub B8_Click(sender As Object, e As EventArgs) Handles B8.Click
Tpantalla.Text = Tpantalla.Text & "8"
End Sub
Private Sub B9_Click(sender As Object, e As EventArgs) Handles B9.Click
Tpantalla.Text = Tpantalla.Text & "9"
End Sub

Private Sub MultiHandler_NumericButtons_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles Button_Num1.Click, Button_Num2.Click, Button_Num3.Click,
Button_Num4.Click, Button_Num5.Click, Button_Num6.Click,
Button_Num7.Click, Button_Num8.Click, Button_Num9.Click,
Button_Num0.Click
Me.TextBox_CalcDisplay.AppendText(DirectCast(sender, Button).Text)
End Sub