Merancang Program Kalkulator dengan VB .Net

Public Class Form1
    Dim str1 As Double
    Dim str2 As Double
    Dim str As String

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

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

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

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

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

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

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

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

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

    Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click
        TextBox1.Text += Button15.Text
    End Sub

    Private Sub Button16_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button16.Click
        TextBox1.Text += Button16.Text
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'TextBox1.Enabled = False
        'TextBox1.MaxLength = 20
    End Sub

    Private Sub Button17_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button17.Click
        TextBox1.Text += Button17.Text
    End Sub

    Private Sub Button18_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button18.Click
        TextBox1.Text = ""
        str = ""
    End Sub
    Private Sub Button14_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click
        'str = Val(TextBox1.Text)
        str2 = Val(TextBox1.Text)
        If str = "-" Then
            TextBox1.Text = str1 - str2
        ElseIf str = "+" Then
            TextBox1.Text = str1 + str2
        ElseIf str = "*" Then
            TextBox1.Text = str1 * str2
        ElseIf str = "/" Then
            TextBox1.Text = str1 / str2
        End If

    End Sub

    Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click
        str1 = Val(TextBox1.Text)
        TextBox1.Text = ""
        str = Button10.Text
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs)
        Label1.Text = TimeOfDay
    End Sub

    Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button11.Click
        str1 = Val(TextBox1.Text)
        TextBox1.Text = ""
        str = Button11.Text
    End Sub

    Private Sub Button12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button12.Click
        str1 = Val(TextBox1.Text)
        TextBox1.Text = ""
        str = Button12.Text
    End Sub

    Private Sub Button13_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click
        str1 = Val(TextBox1.Text)
        TextBox1.Text = ""
        str = Button13.Text
    End Sub
End Class