Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
        'Declare Variables for the calculations.
        Dim intPackageAQty As Integer
        Dim intPackageBQty As Integer
        Dim intPackageCQty As Integer
        Dim decAtotal As Decimal
        Dim decBtotal As Decimal
        Dim decCtotal As Decimal
        Dim decGrandTotal As Decimal

        Const decPackageDiscount10to19 As Decimal = 0.2
        Const decPacakgeDiscount50to99 As Decimal = 0.4
        Const decPackageDiscount20to49 As Decimal = 0.3
        Const decPackageDiscountOver100 As Decimal = 0.5
        Const decAprice As Decimal = 99
        Const decBprice As Decimal = 199
        Const decCprice As Decimal = 299



        If IsNumeric(txtPackageA.Text) = False Then
            lblErrorMessage.Text = "Quantity amount must be numberic. Negative numbers are also not accepted"
            lblErrorMessage.Visible = True
            Return
        End If

        If IsNumeric(txtPackageB.Text) = False Then
            lblErrorMessage.Text = "Quantity amount must be numberic. Negative numbers are also not accepted"
            lblErrorMessage.Visible = True
            Return
        End If

        If IsNumeric(txtPackageC.Text) = False Then
            lblErrorMessage.Text = "Quantity amount must be numberic. Negative numbers are also not accepted"
            lblErrorMessage.Visible = True
            Return
        End If

        ' Past this point, the user inputs contain software quantities.
        'Hide the error message label and do the calculations for
        'Package A.
        lblErrorMessage.Visible = False


        'calculating total price per package with discounts
        Select Case intPackageAQty
            Case Is < 10
                decAtotal = intPackageAQty * decAprice
            Case 10 To 19
                decAtotal = (intPackageAQty * decAprice) * decPackageDiscount10to19
            Case 20 To 49
                decAtotal = (intPackageAQty * decAprice) * decPackageDiscount20to49
            Case 50 To 99
                decAtotal = (intPackageAQty * decAprice) * decPacakgeDiscount50to99
            Case Is >= 100
                decAtotal = (intPackageAQty * decAprice) * decPackageDiscountOver100
        End Select
        Select Case intPackageBQty
            Case Is < 10
                decBtotal = intPackageBQty * decBprice
            Case 10 To 19
                decBtotal = (intPackageBQty * decBprice) * decPackageDiscount10to19
            Case 20 To 49
                decBtotal = (intPackageBQty * decBprice) * decPackageDiscount20to49
            Case 50 To 99
                decBtotal = (intPackageBQty * decBprice) * decPacakgeDiscount50to99
            Case Is >= 100
                decBtotal = (intPackageBQty * decBprice) * decPackageDiscountOver100
        End Select
        Select Case intPackageCQty
            Case Is < 10
                decCtotal = intPackageCQty * decCprice
            Case 10 To 19
                decCtotal = (intPackageBQty * decCprice) * decPackageDiscount10to19
            Case 20 To 49
                decCtotal = (intPackageBQty * decCprice) * decPackageDiscount20to49
            Case 50 To 99
                decCtotal = (intPackageBQty * decCprice) * decPacakgeDiscount50to99
            Case Is >= 100
                decAtotal = (intPackageBQty * decCprice) * decPackageDiscountOver100
        End Select

class my1
  Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
  dim pacA as new my2
  dim pacB as new my2
  dim pacC as new my2

  if pacA.isNR=false or pacB.isNR=false or pacC.isNR=false then
      lblErrorMessage.Text = "Quantity amount must be numberic. Negative numbers are also not accepted"
            lblErrorMessage.Visible = True
            Return
  else
      decAtotal=pacA.decTot
      decBtotal=pacB.decTot
      decCtotal=pacC.decTot
  end if

  end sub
end class
class my2
        Const decPackageDiscount10to19 As Decimal = 0.2
        Const decPacakgeDiscount50to99 As Decimal = 0.4
        Const decPackageDiscount20to49 As Decimal = 0.3
        Const decPackageDiscountOver100 As Decimal = 0.5
        Const decAprice As Decimal = 99
        Const decBprice As Decimal = 199
        Const decCprice As Decimal = 299

        Dim intPackageQty As Integer
        Dim dectotal As Decimal
        Dim decprice As Decimal

        Public Property Total() As Decimal
           Get
              Return dectotal
           End Get
           Set(ByVal Value As Decimal)
              dectotal = value
           End Set
        End Property

        Public Property Price() As Decimal
           Get
              Return dectotal
           End Get
           Set(ByVal Value As Decimal)
              dectotal = value
           End Set
        End Property

        Public Property Package() As Integer
           Get
              Return intPackageQty
           End Get
           Set(ByVal Value As Integer)
              intPackageQty = value
              Select Case value
                 Case Is < 10: dectotal = value * decprice
                 Case 10 To 19:dectotal = value * decprice * decPackageDiscount10to19
            Case 20 To 49:dectotal = value * decprice * decPackageDiscount20to49
            Case 50 To 99:dectotal = value * decprice * decPacakgeDiscount50to99
            Case Is >= 100:dectotal = value * decprice * decPackageDiscountOver100
        End Select
           End Set
        End Property
end class