Partial Public Class _Default
    Inherits System.Web.UI.Page

    Dim parsedValue As Integer

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Label1.Text = Integer.Parse(0)
    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
        If (Int32.TryParse(TextBox1.Text, parsedValue) And Int32.TryParse(TextBox2.Text, parsedValue)) Then
            'Add the 2 numbers entered
            Label1.Text = Integer.Parse(Me.TextBox1.Text) + Integer.Parse(Me.TextBox2.Text)
        Else
            Label1.Text = Integer.Parse(0)
        End If
    End Sub

    Protected Sub Button2_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button2.Click
        If (Int32.TryParse(TextBox1.Text, parsedValue) And Int32.TryParse(TextBox2.Text, parsedValue)) Then
            'Subtract one number from the other
            Label1.Text = Integer.Parse(Me.TextBox1.Text) - Integer.Parse(Me.TextBox2.Text)
        Else
            Label1.Text = Integer.Parse(0)
        End If
    End Sub

    Protected Sub Button3_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button3.Click
        If (Int32.TryParse(TextBox1.Text, parsedValue) And Int32.TryParse(TextBox2.Text, parsedValue)) Then
            'Multiply the 2 numbers entered
            Label1.Text = Integer.Parse(Me.TextBox1.Text) * Integer.Parse(Me.TextBox2.Text)
        Else
            Label1.Text = Integer.Parse(0)
        End If
    End Sub

    Protected Sub Button4_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button4.Click
        If (Int32.TryParse(TextBox1.Text, parsedValue) And Int32.TryParse(TextBox2.Text, parsedValue)) Then
            'Divide the 2 numbers entered
            Label1.Text = Integer.Parse(Me.TextBox1.Text) / Integer.Parse(Me.TextBox2.Text)
        Else
            Label1.Text = Integer.Parse(0)
        End If
    End Sub
End Class