Калькулятор на VisualBasic - VB

Public Class Form1
    Dim a As String
    Dim b As String
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        a = TextBox1.Text
        TextBox2.Text = "+"
        TextBox1.Text = ""

    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        a = TextBox1.Text
        TextBox2.Text = "-"
        TextBox1.Text = ""

    End Sub
 
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        a = TextBox1.Text
        TextBox2.Text = "*"
        TextBox1.Text = ""

    End Sub
 
    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        a = TextBox1.Text
        TextBox2.Text = "/"
        TextBox1.Text = ""

    End Sub

    Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click

        TextBox1.Text = ""
        TextBox2.Text = ""
 
    End Sub
 
    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        TextBox1.Text = TextBox1.Text & "1"
    End Sub
 
    Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        TextBox1.Text = TextBox1.Text & "2"
    End Sub
 
    Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
        TextBox1.Text = TextBox1.Text & "3"
    End Sub
 
    Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
        TextBox1.Text = TextBox1.Text & "4"
    End Sub
 
    Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
        TextBox1.Text = TextBox1.Text & "5"
    End Sub
 
    Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click
        TextBox1.Text = TextBox1.Text & "6"
    End Sub
 
    Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button11.Click
        TextBox1.Text = TextBox1.Text & "7"
    End Sub
 
    Private Sub Button12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button12.Click
        TextBox1.Text = TextBox1.Text & "8"
    End Sub
 
    Private Sub Button13_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click
        TextBox1.Text = TextBox1.Text & "9"
    End Sub
 
    Private Sub Button14_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click
        TextBox1.Text = TextBox1.Text & "0"
    End Sub
 
    Private Sub Button16_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button16.Click
        b = TextBox1.Text
        If TextBox2.Text = "*" Then
            TextBox1.Text = a * b
        End If
        If TextBox2.Text = "/" Then
            TextBox1.Text = a / b
        End If
        If TextBox2.Text = "-" Then
            TextBox1.Text = a - b
        End If
    End Sub
End Class

Dim a As String
Dim b As String

Dim a As Integer
Dim b As Integer