Dim decEXTRAmin As Decimal
        Dim decTotalCostofCharges As Decimal
        Dim decNumOfmin As Decimal

        decNumOfmin = 0
        decTotalCostofCharges = 0
        decEXTRAmin = 0

        Me.lblTotalBillz.Text = ""
        Me.Label3.Visible = False
        Me.Label7.Visible = False


        If IsNumeric(Me.txtNumOfMin.Text) Then
            decNumOfmin = Convert.ToDecimal(Me.txtNumOfMin.Text)
        Else
            MsgBox("Enter a Numerical Value.", 21, "Input Error.")
            Me.txtNumOfMin.Text = ""
            Me.txtNumOfMin.Focus()
            Me.lblTotalBillz.Text = ""
            Me.lblXtraMin.Text = ""
            Me.Label3.Visible = False
            Me.Label8.Visible = False
            Me.Label7.Visible = False
        End If

        If decNumOfmin > 300 Then
            decEXTRAmin = decNumOfMin - 300
            Me.lblXtraMin.Text = (decEXTRAmin * _cdecExtraMinFee)
            decTotalCostofCharges = (decEXTRAmin * _cdecExtraMinFee) + _cdecFee + _cdecRegCharge
            Me.lblTotalBillz.Text = decTotalCostofCharges
            Me.Label3.Visible = True
            Me.Label8.Visible = True
            Me.Label7.Visible = True

        End If

        If decNumOfmin < 300 And decNumofMin > 0 Then
            decTotalCostofCharges = _cdecFee + _cdecRegCharge
            Me.lblXtraMin.Text = ""
            Me.lblTotalBillz.Text = decTotalCostofCharges
            Me.Label3.Visible = False
            Me.Label8.Visible = False
            Me.Label7.Visible = True
        End If

        If decnumofmin < 0 Then
            MsgBox("You entered " & decNumOfmin.ToString() & ". Enter A Positive Number.", 21, "Input Error")
            Me.txtNumOfMin.Text = ""
            Me.txtNumOfMin.Focus()
            Me.lblTotalBillz.Text = ""
            Me.lblXtraMin.Text = ""
            Me.Label3.Visible = False
            Me.Label8.Visible = False
            Me.Label7.Visible = False
        End If