Help with application

[OT79]

I have two forms; frmMain & frmReport. I have the following coding for ensuring that the numeric data entered into each of the TextBoxes in in the correct format:

Private Sub btnPurchase_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPurchase.Click
txtRef.Text = Format(CInt(txtRef.Text), "000000")
nudProductType.Text = Format(CStr(nudProductType.Text), "0")
txtWeight.Text = Format(CInt(txtWeight.Text), "0000")
txtQuantity.Text = Format(CInt(txtQuantity.Text), "0000")
nudCalcMeth.Text = Format(CStr(nudCalcMeth.Text), "0")
txtBuy.Text = Format(CInt(txtBuy.Text), "0000")
txtSale.Text = Format(CInt(txtSale.Text), "0000")

My first question is that this is VB6 and I would like to know a better way of coding this event process?

Following on from this I then have all the data saved to a string which is then saved to a *txt file:

Private Sub btnPurchase_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPurchase.Click
txtRef.Text = Format(CInt(txtRef.Text), "000000")
nudProductType.Text = Format(CStr(nudProductType.Text), "0")
txtWeight.Text = Format(CInt(txtWeight.Text), "0000")
txtQuantity.Text = Format(CInt(txtQuantity.Text), "0000")
nudCalcMeth.Text = Format(CStr(nudCalcMeth.Text), "0")
txtBuy.Text = Format(CInt(txtBuy.Text), "0000")
txtSale.Text = Format(CInt(txtSale.Text), "0000")


Dim TotalSalesFile As String
'put fields together to go to Sales Text File
TotalSalesFile = txtRef.Text & nudProductType.Text _
& txtWeight.Text & txtQuantity.Text & nudCalcMeth.Text _
& txtBuy.Text & txtSale.Text

FileOpen(1, "TotalSalesFile.txt", OpenMode.Append)
PrintLine(1, TotalSalesFile)
FileClose(1)


If MessageBox.Show("Click Yes or No", "Reset", MessageBoxButtons.YesNo) = DialogResult.Yes Then
If MessageBox.Show("Do you wish to clear this purchase?", "Reset", MessageBoxButtons.YesNoCancel) = DialogResult.Yes Then
'Clears existing purchase
txtRef.Text = ""
nudProductType.Text = ""
txtWeight.Text = ""
txtQuantity.Text = ""
nudCalcMeth.Text = ""
txtBuy.Text = ""
txtSale.Text = ""
Else
End If
End If

My second form, frmReport is to read the TotalSalesFile.txt and display the data. My problem here is that I have a NumericUpDown (nudCalcMeth), which has two options (1 or 2) Therefore this is calculated as follows:

Calculation Method 1 Weight * Price
Calculation Method 2 Quantity * Price

My second form has to perfom these calculation when it load and the using Tab print the data. I totaly unsure of how to do this and would very much appreciate someones assistance.

I have included the app in case someone wants to view it and give feedback.

Many thanks