Codigo de una calculadura para visual basic

Este es el codigo para una calculadora basica en visual basic, en la cual se maneja un textbox y 18 buttons los cuales son los 10 numeros 0-9, las 4 operaciones aritmeticas, el punto, un C (clear),el igual y un off para parar el programa.

Option explicit on
Dim firstnumber As Single
Dim secondnumber As Single
Dim answernumber As Single
Dim arithmeticprocess As String
Private Subdivision_Click()
firstnumber = Val(pantalla.Text)
pantalla.Text = "0"
arithmeticprocess = "/"
End Sub

Private Sub igual_Click()
secondnumber = Val(pantalla.Text)
If arithmeticprocess = "+" Thenanswernumber = firstnumber + secondnumber
End If
If arithmeticprocess = "-" Then
answernumber = firstnumber - secondnumber
End If
If arithmeticprocess = "x" Then
answernumber = firstnumber *secondnumber
End If
If arithmeticprocess = "/" Then
If secondnumber = 0 Then
MsgBox ("No se puede divir entre cero")
Exit Sub
End If
answernumber = firstnumber / secondnumber
End If
pantalla.Text =answernumber
End Sub

Private Sub limpiar_Click()
pantalla.Text = "0"
End Sub

Private Sub multiplicacion_Click()
firstnumber = Val(pantalla.Text)
pantalla.Text = "0"
arithmeticprocess = "x"End Sub

Private Sub num0_Click()
pantalla.Text = pantalla.Text & "0"
End Sub

Private Sub num1_Click()
pantalla.Text = pantalla.Text & "1"
End Sub

Private Sub num2_Click()
pantalla.Text= pantalla.Text & "2"
End Sub

Private Sub num3_Click()
pantalla.Text = pantalla.Text & "3"
End Sub

Private Sub num4_Click()
pantalla.Text = pantalla.Text & "4"
End Sub

Private Subnum5_Click()
pantalla.Text = pantalla.Text & "5"
End Sub

Private Sub num6_Click()
pantalla.Text = pantalla.Text & "6"
End Sub

Private Sub num7_Click()
pantalla.Text = pantalla.Text & "7"
EndSub

Private Sub num8_Click()
pantalla.Text = pantalla.Text & "8"
End Sub

Private Sub num9_Click()
pantalla.Text = pantalla.Text & "9"
End Sub

Private Sub punto_Click()
pantalla.Text =...