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 Private Sub btnCalc_Click(sender As Object, e As EventArgs) Handles btnCalc.Click

        Const strprompt As String = "Enter sales amount." & ControlChars.NewLine & "Click cancel or leave blank to end."
        Const strTITTLE As String = "Sales entry"
        Dim strInputSales As String
        Dim decSales As Decimal
        Dim intNumSales As Integer
        Dim decTotalSales As Decimal
        Dim decAvgSales As Decimal

        strInputSales = InputBox(strprompt, strTITTLE, "0")

        Do While strInputSales <> String.Empty

            Decimal.TryParse(strInputSales, decSales)

            txtList.Text = txtList.Text & decSales.ToString("N2") & ControlChars.NewLine

            intNumSales = intNumSales + 1
            decTotalSales = decTotalSales + decSales

            strInputSales = InputBox(strprompt, strTITTLE)

        Loop

        If intNumSales > 0 Then
            decAvgSales = decTotalSales / intNumSales
            lblAvg.Text = decAvgSales.ToString("C2")
        Else
            lblAvg.Text = "N/A"
        End If
    End Sub