MDAS Calculation Using a Class

Public Class calculate
    'declare a private variable as a double
    Private _num1 As Double
    Private _num2 As Double
    Private _total As Double
 
    'set a readonly property for the total of the MDAS
    ReadOnly Property total() As Double
        Get
            Return _total 'return the total
        End Get
    End Property
    'create a property for a private variable so that you can access it
    Property num1() As Double
        Get
            Return _num1  'return the first value
        End Get
        Set(ByVal value As Double)
            _num1 = value 'set the first value
        End Set
    End Property
    Property num2() As Double
        Get
            Return _num2
        End Get
        Set(ByVal value As Double)
            _num2 = value
        End Set
    End Property
 
    'create the sub procedures of the MDAS
    Public Sub multiply()
        'formula of multiplication
        _total = num1 * num2
    End Sub
    Public Sub divide()
        'formula of division
        _total = num1 / num2
    End Sub
    Public Sub add()
        'formula of addition
        _total = num1 + num2
    End Sub
    Public Sub subtract()
        'formula of subtraction
        _total = num1 - num2
    End Sub  
End Class

Public Class Form1
 
    'create a sub procedure for the events of clicking the radio button that handles all of it.
    Private Sub RadioButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) _
     Handles Radio_Subtaction.Click, Radio_Multiplication.Click, Radio_Division.Click, Radio_Addition.Click
 
        'call a constructor method and return to cal as an instance of a class
        Dim cal As calculate = New calculate()
 
        'declaring the string variable represent as a textbox
        Dim txtnum1 As String = TextBox1.Text
        Dim txtnum2 As String = TextBox2.Text
        'declaring the double variable
        Dim dbl_val1 As Double
        Dim dbl_val2 As Double
 
        If IsNumeric(txtnum1) And IsNumeric(txtnum2) Then 'check if the textbox has a numeric value
            'convert the string to double
            dbl_val1 = Double.Parse(txtnum1)
            dbl_val2 = Double.Parse(txtnum2)
 
            'get the value of the converted variable 
            'to pass it into the variable in the class
            cal.num1 = dbl_val1
            cal.num2 = dbl_val2
 
            'the condition is, if the radiobutton is clicked, 
            'the operation of MDAS executes.
            If Radio_Multiplication.Checked Then
                'result:
                cal.multiply() 'call a subname in a class for multiplying
            ElseIf Radio_Division.Checked Then
                'result:
                cal.divide() 'call a subname in a class for dividing
            ElseIf Radio_Addition.Checked Then
                'result:
                cal.add() 'call a subname in a class for adding
            ElseIf Radio_Subtaction.Checked Then
                'result:
                cal.subtract() 'call a subname in a class for subtracting
            End If
        Else
            'the result is: 
            'if the textbox is empty or has a string value
            TextBox3.Text = "Enter a number"
            Return
        End If
        'put the result of the MDAS to a textbox.
        TextBox3.Text = cal.total()
    End Sub
End Class