how to find the total in gridview columns
<p>I would like your help with my code.
I wrote this source code</p>

<pre><code>&lt;%@ Page Language="C#" AutoEventWireup="true" CodeFile="ShowLand.aspx.cs" Inherits="ShowLand" %&gt;

&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;

&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
&lt;head runat="server"&gt;
    &lt;title&gt;&lt;/title&gt;
&lt;/head&gt;
&lt;body MS_POSITIONING="GridLayout" bgColor="#FFF8DC" aLink="#330066"&gt;
    &lt;form id="form1" runat="server"&gt;
 &lt;asp:Label id="Label6" 
        style="Z-INDEX: 101; LEFT: 176px; POSITION: absolute; TOP: 8px; text-align: center;" runat="server"
                Font-Size="X-Large" Font-Italic="True" Font-Underline="True" Width="608px" ForeColor="Navy"
                Font-Bold="True"&gt;Land For Sale&lt;/asp:Label&gt;
    &lt;br /&gt;
    &lt;br /&gt;
    &lt;br /&gt;
&lt;div&gt;
        &lt;asp:GridView ID="gridView1" runat="server" CellPadding="4" ForeColor="#333333" 
            GridLines="None"&gt;
            &lt;AlternatingRowStyle BackColor="White" ForeColor="#284775" /&gt;
            &lt;Columns&gt;
                &lt;asp:TemplateField&gt;
                    &lt;ItemTemplate&gt;
                        &lt;asp:CheckBox ID="chkSelect" runat="server" /&gt;
                        &lt;asp:HiddenField ID="hdValue" runat="server" Value='&lt;%#Eval("ID") %&gt;' /&gt;
                    &lt;/ItemTemplate&gt;
                &lt;/asp:TemplateField&gt;
            &lt;/Columns&gt;
            &lt;EditRowStyle BackColor="#999999" /&gt;
            &lt;FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /&gt;
            &lt;HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /&gt;
            &lt;PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" /&gt;
            &lt;RowStyle BackColor="#F7F6F3" ForeColor="#333333" /&gt;
            &lt;SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" /&gt;
            &lt;SortedAscendingCellStyle BackColor="#E9E7E2" /&gt;
            &lt;SortedAscendingHeaderStyle BackColor="#506C8C" /&gt;
            &lt;SortedDescendingCellStyle BackColor="#FFFDF8" /&gt;
            &lt;SortedDescendingHeaderStyle BackColor="#6F8DAE" /&gt;
        &lt;/asp:GridView&gt;
    &lt;/div&gt;
    &lt;div&gt;
        &lt;asp:Button ID="btnMove" runat="server" Text="Add To Cart" OnClick="btnMove_Click" /&gt;
    &lt;/div&gt;
    &lt;div&gt;

        &lt;asp:GridView ID="gridView2" runat="server" CellPadding="4" ForeColor="#333333" 
            GridLines="None"&gt;
            &lt;AlternatingRowStyle BackColor="White" ForeColor="#284775" /&gt;
        &lt;Columns&gt;
        &lt;asp:TemplateField HeaderText="Qty"&gt;
            &lt;ItemTemplate&gt;
            &lt;asp:TextBox ID="tbQty" runat="server" Width="25px"
            MaxLength="3" /&gt;
            &lt;/ItemTemplate&gt;
            &lt;ItemStyle Width="25px" HorizontalAlign="Center"/&gt;
        &lt;/asp:TemplateField&gt;
        &lt;/Columns&gt;
            &lt;EditRowStyle BackColor="#999999" /&gt;
            &lt;FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /&gt;
            &lt;HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /&gt;
            &lt;PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" /&gt;
            &lt;RowStyle BackColor="#F7F6F3" ForeColor="#333333" /&gt;
            &lt;SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" /&gt;
            &lt;SortedAscendingCellStyle BackColor="#E9E7E2" /&gt;
            &lt;SortedAscendingHeaderStyle BackColor="#506C8C" /&gt;
            &lt;SortedDescendingCellStyle BackColor="#FFFDF8" /&gt;
            &lt;SortedDescendingHeaderStyle BackColor="#6F8DAE" /&gt;
        &lt;/asp:GridView&gt;
    &lt;/div&gt;
    &lt;br /&gt;
    &lt;br /&gt;
    &lt;br /&gt;
    &lt;/form&gt;
&lt;/body&gt;

&lt;/html&gt;
</code></pre>

<p>and also i created these 2 gridviews like this in ShowLand.aspx.cs</p>

<pre><code>using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;

public partial class ShowLand : System.Web.UI.Page
{
    const string key = "MyDataSource3";
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            BindGridView();
        }

    }
    private void BindGridView()
    {
        if (Session[key] == null)
        {
            gridView1.DataSource = GetDataSource();
            gridView1.DataBind();
        }
        else
        {
            gridView1.DataSource = (DataTable)Session[key];
            gridView1.DataBind();
        }

    }
    protected DataTable GetDataSource()
    {
        try
        {
            DataTable dt = new DataTable();
            dt = new DataTable();
            dt.Columns.Add("ID", typeof(int)).AutoIncrement = true;
            dt.Columns.Add("Name", typeof(string));
            dt.Columns.Add("Price(Grouch)/Hectares", typeof(float));
            DataColumn[] keys = new DataColumn[2];
            keys[0] = dt.Columns["ID"];
            dt.PrimaryKey = keys;
            dt.Rows.Add("1", "Seaside Location", 1.5);
            dt.Rows.Add("2", "Arable Land", 0.1);
            dt.Rows.Add("3", "Foothills of the mountains", 1.5);
            dt.Rows.Add("4", "Industrial Land", 0.1);
            dt.Rows.Add("5", "Rolling Farmland", 0.5);
            Session[key] = dt;
            return dt;

        }
        catch
        {
            return null;
        }
    }
    protected void btnMove_Click(object sender, EventArgs e)
    {
        try
        {
            DataTable dtMain = Session[key] as DataTable;
            //copy the schema of source table
            DataTable dtClone = dtMain.Clone();
            foreach (GridViewRow gv in gridView1.Rows)
            {
                CheckBox chk = gv.FindControl("chkSelect") as CheckBox;
                HiddenField hdValue = gv.FindControl("hdValue") as HiddenField;
                if (chk.Checked)
                {
                    //get only the rows you want
                    DataRow[] results = dtMain.Select("ID=" + hdValue.Value + "");
                    //populate new destination table
                    foreach (DataRow dr in results)
                    {
                        dtClone.ImportRow(dr);
                    }
                }
                gridView2.DataSource = dtClone;
                gridView2.DataBind();
            }
        }
        catch
        {
            BindGridView();
        }

    }
}
</code></pre>

<p>In this code the user can chose with the checkbox his choice and with the button to add this choice in the second gridview.Also in the textbox can give the quantity.
I would like to find a way how to multiply the quantity with the price column.How can i do that?</p>
