Simple Caculator

Public Class Form1
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 
        If (TextBox1.Text = " ") Then
            MessageBox.Show("enter value in num1")
        End If
        If (TextBox2.Text = " ") Then
            MessageBox.Show("enter value in num2")
        Else
            TextBox3.Text = Val(TextBox1.Text) + Val(TextBox2.Text)
        End If
 
    End Sub
 
    Private Sub TextBox3_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox3.TextChanged
 
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
 
        If (TextBox1.Text = " ") Then
            MessageBox.Show("enter value in num1")
        End If
        If (TextBox2.Text = " ") Then
            MessageBox.Show("enter value in num2")
        Else
            TextBox3.Text = Val(TextBox1.Text) * Val(TextBox2.Text)
        End If
    End Sub
 
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        TextBox1.Text = "  "
        TextBox2.Text = "  " 'clear button to clear all numbers.
        TextBox3.Text = " "
 
 
 
    End Sub
 
    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        Form2.Show()     'show exit form.
    End Sub
 
 
    Private Sub abstract_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles abstract.Click
        If (TextBox1.Text = " ") Then
            MessageBox.Show("enter value in num1")
        End If
        If (TextBox2.Text = " ") Then
            MessageBox.Show("enter value in num2")
        Else
            TextBox3.Text = Val(TextBox1.Text) - Val(TextBox2.Text)
        End If
 
    End Sub
 
    Private Sub division_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles division.Click
        If (TextBox1.Text = " ") Then
            MessageBox.Show("enter value in num1")
        End If
        If (TextBox2.Text = " ") Then
            MessageBox.Show("enter value in num2")
        Else
            TextBox3.Text = Val(TextBox1.Text) / Val(TextBox2.Text)
        End If
    End Sub
 
    Private Sub TextBox4_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
 
    End Sub
End Class
 
Public Class Form2
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Me.Close()    ' if no button close form2 &keep app on.
 
 
 
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 
        Form1.Close()  'close form1.
 
        Me.Close()  'close form2 .
 
 
 
    End Sub
 
    Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
    End Sub
End Class