multiplying and coding for derived attributes to appear whenever 2 attributes will be mutiplied

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VB

I have a table w/c is in the data grid view... it has 4 attributes ID,Description,Unit Price and Unit Quanity... now part of the task is whenever New record was added, automatically the Unit Price and The Unit Quantity will be multiplied and a derived attribute w/c is Total Price will appear ... What Code will I use to perform this and where will it will inserted?

Imports System.Data.OleDb
Public Class frmMain

    Dim myconnection As New OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=G:\order\Order\Order\Orders.accdb")

    Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim sql As String
        myconnection.Open()

        sql = " Select * from Orders"

        Dim da As New OleDb.OleDbDataAdapter(sql, myconnection)
        Dim dt As New DataTable("tblOrder")

        da.Fill(dt)
        dgv1.DataSource = dt.DefaultView
        RefreshDGV()

        myconnection.Close()


    End Sub


    Private Sub txtSearch_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtSearch.TextChanged
        Dim sqlsearch As String
        sqlsearch = "SELECT * FROM Orders WHERE ID LIKE '%" & txtSearch.Text & "%'" & " OR Description LIKE '%" & txtSearch.Text & "%'"

        Dim da As New OleDbDataAdapter(sqlsearch, myconnection)
        Dim dt As New DataTable("Orders")
        da.Fill(dt)
        dgv1.DataSource = dt.DefaultView


    End Sub

    Private Sub cboSearch_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cboSearch.SelectedIndexChanged
        

        If Not cboSearch.Text = cboSearch.SelectedText Then
            btnSave.Enabled = True
        End If


        Dim MyVariable As String

        MyVariable = cboSearch.Text

        MsgBox(MyVariable)

    End Sub

    Private Sub btnAdd_Click(sender As System.Object, e As System.EventArgs) Handles btnAdd.Click
        frmAdd.Show()
    End Sub

    Private Sub RefreshDGV()

    End Sub

    Private Sub btnSave_Click(sender As System.Object, e As System.EventArgs) Handles btnSave.Click

      
       
    End Sub
End Class