how to pass values to another page using query string

Question

in design i have  two pages.

in first design page i have two textboxes

Number1  10(textbox1)

Number2  12(textbox2)

first design page code as follows

using System;

using System.Data;

using System.Configuration;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page 

{

    protected void Page_Load(object sender, EventArgs e)

    {

        string number1   = Request.QueryString[0];

        string number2 = Request.QueryString[1];

        int result = Convert.ToInt32(number1) + Convert.ToInt32(number2);

        //TextBox1.Text = result.ToString();

    }

    protected void LinkButton1_Click(object sender, EventArgs e)

    {

        string urltoNaviget = " ~/Add.aspx?Number1=" + txt_name.Text + "&Number2=" + txt_age.Text;

        LinkButton1.PostBackUrl = urltoNaviget;

    }

}

In Second design  page i have one textbox

Adding Two numbers    22(textbox1)

Second  design page code as follows

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Data.SqlClient;

public partial class Default2 : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        string number1 = Request.QueryString[0];

        string number2 = Request.QueryString[1];

        // The other way to Read the values 

        //string number1 = Request.QueryString["Number1"];

        //string number2 = Request.QueryString["Number2"];

        int result = Convert.ToInt32(number1) + Convert.ToInt32(number2);

        TextBox1.Text = result.ToString();

    }

}

When i run i have following error as follows

Index was out of range. Must be non-negative and less than the size of the collections.

Parameter name: index 

Please help me

thanks,

Rao.,