Как сделать, чтобы, когда я нажимаю на"+", они добавляют два числа .

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'numbers are declare in textbox1 .the addition of two numbers using + and = sing
Public Class Form1

    Dim num1 As Double
    Dim num2 As Double
    Dim operation As Double
    Dim oprationsec As Boolean = False
    Dim ans As Double


    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "1"
        Else
            TextBox1.Text = "1"
        End If
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "2"
        Else
            TextBox1.Text = "2"
        End If
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "3"
        Else
            TextBox1.Text = "3"
        End If
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "4"
        Else
            TextBox1.Text = "4"
        End If
    End Sub

    Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "5"
        Else
            TextBox1.Text = "5"
        End If
    End Sub

    Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "6"
        Else
            TextBox1.Text = "6"
        End If
    End Sub

    Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "7"
        Else
            TextBox1.Text = "7"
        End If
    End Sub

    Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "8"
        Else
            TextBox1.Text = "8"
        End If
    End Sub

    Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "9"
        Else
            TextBox1.Text = "9"
        End If
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If TextBox1.Text <> "0" Then
            TextBox1.Text += "0"
        End If
    End Sub

    Private Sub Button16_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button16.Click
        TextBox1.Text = "0"
    End Sub

    Private Sub Button13_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click
        num1 = TextBox1.Text
        TextBox1.Text = "0"
        oprationsec = True
        operation = 1
    End Sub

    Private Sub Button14_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click
        num1 = TextBox1.Text
        TextBox1.Text = "0"
        oprationsec = True
        operation = 2
    End Sub

    Private Sub Button12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button12.Click
        num1 = TextBox1.Text
        TextBox1.Text = "0"
        oprationsec = True
        operation = 3
    End Sub

    Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button11.Click
        num1 = TextBox1.Text
        TextBox1.Text = "0"
        oprationsec = True
        operation = 4
    End Sub

    Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click
        If oprationsec = True Or TextBox1.Text <> IsNumeric(TextBox1.Text > 0) Then
            num2 = TextBox1.Text
            If operation = 1 Then
                TextBox1.Text = num1 + num2
            ElseIf operation = 2 Then
                TextBox1.Text = num1 - num2
            ElseIf operation = 3 Then
                TextBox1.Text = num1 / num2
            ElseIf operation = 4 Then
                TextBox1.Text = num1 * num2
            Else
                If num2 = 0 Then
                    TextBox1.Text = "Error"
                End If
            End If
            oprationsec = False
        Else
            TextBox1.Text = "Error"
        End If
    End Sub

    Private Sub Button18_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button18.Click
        If Not (TextBox1.Text.Contains(".")) Then
            TextBox1.Text += "."
        End If
    End Sub

    Private Sub Button17_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button17.Click
        num1 = TextBox1.Text
        TextBox1.Text = "0"
        oprationsec = True
        operation = 1
    End Sub
End Class

Что я уже пробовал:

сначала добавьте число после "+" пойте после добавления второго числа, а затем нажмите на "=" Я получил дополнение, но когда как сделать дополнение только только "+" пойте

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