Quick and Simple Calculator

'Author: http://facebook.com/ruda.gabriel'
'Fórum: http://www.teamgamehacks.com/BR/forum/forum.php'

Public Class Form1
    Friend WithEvents TextIn, Textbox1 As New TextBox
    Friend WithEvents btnSum, btnSubtract, btnDivide, _
    btnMultiply, btnEqual, btnClear As New Button
    Friend WithEvents RdSum, RdSubtract, RdMultiply, _
    RdDivide As New RadioButton
    Private Sub BtnEqual_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnEqual.Click
        Textbox1.Focus()
        Textbox1.DeselectAll()
        If RdSum.Checked = True Then
            If TextIn.Text = String.Empty Then
                Exit Sub
            Else
                Textbox1.Text = Calculator.Sum(Textbox1.Text, TextIn.Text)
                TextIn.Clear()
            End If
        ElseIf RdSubtract.Checked = True Then
            If TextIn.Text = String.Empty Then
                Exit Sub
            Else
                Textbox1.Text = Calculator.Subtract(Textbox1.Text, TextIn.Text)
                TextIn.Clear()
            End If
        ElseIf RdDivide.Checked = True Then
            If TextIn.Text = String.Empty Then
                Exit Sub
            Else
                Textbox1.Text = Calculator.Divide(Textbox1.Text, TextIn.Text)
                TextIn.Clear()
            End If
        ElseIf RdMultiply.Checked = True Then
            If TextIn.Text = String.Empty Then
                Exit Sub
            Else
                Textbox1.Text = Calculator.Multiply(Textbox1.Text, TextIn.Text)
                TextIn.Clear()
            End If
        End If
    End Sub

    Private Sub BtnSum_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnSum.Click
        RdSum.Checked = True
        RdSubtract.Checked = False
        RdMultiply.Checked = False
        RdDivide.Checked = False
        TextIn.Clear()
        TextIn.Text = Textbox1.Text
        Textbox1.Clear()
        Textbox1.Focus()
    End Sub

    Private Sub BtnClear_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnClear.Click
        Textbox1.Clear()
        TextIn.Clear()
        Textbox1.Focus()
    End Sub

    Private Sub BtnSubtract_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnSubtract.Click
        RdSum.Checked = False
        RdSubtract.Checked = True
        RdMultiply.Checked = False
        RdDivide.Checked = False
        TextIn.Clear()
        TextIn.Text = Textbox1.Text
        Textbox1.Clear()
        Textbox1.Focus()
    End Sub

    Private Sub BtnDivide_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnDivide.Click
        RdSum.Checked = False
        RdSubtract.Checked = False
        RdMultiply.Checked = False
        RdDivide.Checked = True
        TextIn.Clear()
        TextIn.Text = Textbox1.Text
        Textbox1.Clear()
        Textbox1.Focus()
    End Sub

    Private Sub BtnMultiply_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnMultiply.Click
        RdSum.Checked = False
        RdSubtract.Checked = False
        RdMultiply.Checked = True
        RdDivide.Checked = False
        TextIn.Clear()
        TextIn.Text = Textbox1.Text
        Textbox1.Clear()
        Textbox1.Focus()
    End Sub

    Private Sub Me_Load(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles MyBase.Load
        Me.Text = "Simple Calculator"
        Me.MaximizeBox = False
        Me.FormBorderStyle = Windows.Forms.FormBorderStyle.FixedToolWindow
        Me.Size = New Size(235, 84)
        Me.Controls.Add(Textbox1)
        Textbox1.Size = New Size(216, 20)
        Textbox1.TextAlign = HorizontalAlignment.Right
        Textbox1.BorderStyle = BorderStyle.FixedSingle
        Textbox1.Location = New Point(6, 5)
        Me.Controls.Add(btnSum)
        btnSum.Size = New Size(31, 20)
        btnSum.Location = New Point(6, 31)
        btnSum.Text = "+"
        Me.Controls.Add(btnSubtract)
        btnSubtract.Size = New Size(31, 20)
        btnSubtract.Location = New Point(43, 31)
        btnSubtract.Text = "-"
        Me.Controls.Add(btnDivide)
        btnDivide.Size = New Size(31, 20)
        btnDivide.Location = New Point(80, 31)
        btnDivide.Text = "/"
        Me.Controls.Add(btnMultiply)
        btnMultiply.Size = New Size(31, 20)
        btnMultiply.Location = New Point(117, 31)
        btnMultiply.Text = "*"
        Me.Controls.Add(btnEqual)
        btnEqual.Size = New Size(31, 20)
        btnEqual.Location = New Point(154, 31)
        btnEqual.Text = "="
        Me.Controls.Add(btnClear)
        btnClear.Size = New Size(31, 20)
        btnClear.Location = New Point(191, 31)
        btnClear.Text = "CE"
    End Sub

    Private Sub Textbox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles Textbox1.TextChanged
        If IsNumeric(Textbox1.Text) = False Then
            Textbox1.Clear()
        End If
    End Sub

End Class
Module Calculator
    Public Function Multiply _
    (ByVal Nmr1 As String, ByVal Nmr2 As String) As Single
        On Error Resume Next
        Return (Nmr1 * Nmr2)
    End Function
    Public Function Sum _
    (ByVal Nmr1 As String, ByVal Nmr2 As String) As Single
        On Error Resume Next
        Return (+Nmr1 + Nmr2)
    End Function
    Public Function Subtract _
    (ByVal Nmr1 As String, ByVal Nmr2 As String) As Single
        On Error Resume Next
        Return -(Nmr1 - Nmr2)
    End Function
    Public Function Divide _
    (ByVal Nmr1 As String, ByVal Nmr2 As String) As Single
        On Error Resume Next
        Return (Nmr1 / Nmr2)
    End Function
End Module