'Declare variable for the calculations.
        Dim decRoomCharges As Decimal               'Room charges total
        Dim decAddCharges As Decimal                'Additional Charges
        Dim decSubtotal As Decimal                  'Subtotal
        Dim decTax As Decimal                       'Tax
        Dim decTotal As Decimal                     'Total of all charges
        Const decTAX_RATE As Decimal = 0.08D        'Tax Rate. Consts CANNOT be changed by a programming statment

        Try
            'Calculate and display the room charges.
            decRoomCharges = CDec(txtNights.Text) *
                             CDec(txtNightlyCharge.Text)    '<---Calculating(mulitplying) the room charges
            lblRoomCharges.Text = decRoomCharges.ToString("c")  '<---Displaying decRoomCharges in lblRoomCharges

            'Calucalt and display the additional charges.
            decAddCharges = CDec(txtRoomService.Text) +
                            CDec(txtTelephone.Text) +
                            CDec(txtMisc.Text)              '<---Calculating(adding) the Additional charges
            lblAddCharges.Text = decAddCharges.ToString("c")    '<---Displayig decAdditionalCharges(decAddCharges
            'in lblAddCharges.

            'Calculate and display the subtotal.
            decSubtotal = decRoomCharges + decAddCharges '<---Calculating the Subtotal
            lblSubtotal.Text = decSubtotal.ToString("c")  '<---Displaying decSubtotal in lblSubtotal

            'Calculate and display the tax.
            decTax = decSubtotal * decTAX_RATE '<---Calculating(multiplying) the Tax
            lblTax.Text = decTax.ToString("c")  '<---Displaying decTax in lblTax

            'Calculate and display the total charges.
            decTotal = decSubtotal + decTax     '<---Calculating(adding) the Total Charges
            lblTotal.Text = decTotal.ToString("c")  '<---Displaying decTotal in lblTotal.

            'Change and display the total charges.
            lblTotal.BackColor = Drawing.Color.Blue
            lblTotal.ForeColor = Drawing.Color.White

        Catch ex As Exception
            'Error message
            MessageBox.Show("All input must be vaild numberic values.")
        End Try