How can we make calculator in vb.net

 This is the simple code of calculator:-

Public Class Form2
    Dim total1 As Integer
    Dim total2 As Integer
    Dim sign As String
    Dim opr As String

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        TextBox1.Text = TextBox1.Text & "0"
    End Sub



    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        TextBox1.Text = TextBox1.Text & "1"
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        TextBox1.Text = TextBox1.Text & "2"
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        TextBox1.Text = TextBox1.Text & "3"
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        TextBox1.Text = TextBox1.Text & "4"
    End Sub

    Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        TextBox1.Text = TextBox1.Text & "5"
    End Sub

    Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
        TextBox1.Text = TextBox1.Text & "6"
    End Sub

    Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
        TextBox1.Text = TextBox1.Text & "7"
    End Sub

    Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
        TextBox1.Text = TextBox1.Text & "8"
    End Sub

    Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click
        total1 = Val(TextBox1.Text)
        opr = "+"
        TextBox1.Text = ""
    End Sub

    Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button11.Click
        total2 = Val(TextBox1.Text)
        Select opr
            Case "+" : TextBox1.Text = total1 + total2
            Case "-" : TextBox1.Text = total1 - total2
            Case "*" : TextBox1.Text = total1 * total2
            Case "/" : TextBox1.Text = total1 / total2
        End Select
    End Sub

    Private Sub Button14_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click
        total1 = Val(TextBox1.Text)
        opr = "*"
        TextBox1.Text = ""
    End Sub

    Private Sub Button13_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click
        total1 = Val(TextBox1.Text)
        opr = "/"
        TextBox1.Text = ""
    End Sub

    Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click
        total1 = Val(TextBox1.Text)
        opr = "-"
        TextBox1.Text = ""
    End Sub

    Private Sub Button12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button12.Click
        TextBox1.Text = ""
    End Sub
End Class