How to calculate number input by each row in gridview

Dear All,

May i know how to calculate input values by each row in gridview ?

Example  input quantity is 10, then generate the serial number for each row quantity is 1  

Actual expect result 

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="WebFormtest2.aspx.cs" Inherits="acmkweb.MM.WebFormtest2" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajax" %>

<asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">


<asp:ScriptManager ID="ScriptManager1" AsyncPostBackTimeOut="3600" runat="server">
</asp:ScriptManager>



<asp:Table ID="QueryTypeTBL" runat="server">





 <asp:TableRow ID="TableRow1" runat="server" ForeColor="Teal">

  <asp:TableHeaderCell BorderColor="Black" BorderWidth="1" BackColor="#0C0C25" ForeColor="White"> Type :</asp:TableHeaderCell> 
            <asp:TableHeaderCell BorderColor="Black" BorderWidth="1" Width="200" HorizontalAlign="Left" ForeColor="Red" BackColor="ControlLight">
             <asp:DropDownList ID="Type" runat="server" AutoPostBack = "False" ></asp:DropDownList>
             <asp:RequiredFieldValidator ID="WMCContTypeRFV" runat="server" ErrorMessage="***" InitialValue="--Select Type--" ControlToValidate="Type" ValidationGroup="Add"></asp:RequiredFieldValidator>
            </asp:TableHeaderCell> 
            </asp:TableRow>





 <asp:TableRow ID="TableRow13" runat="server" ForeColor="Teal">
             <asp:TableHeaderCell BorderColor="Black" BorderWidth="1" BackColor="#0C0C25" ForeColor="White"> Quantity:</asp:TableHeaderCell> 
            <asp:TableHeaderCell BorderColor="Black" BorderWidth="1" Width="200" HorizontalAlign="Left" ForeColor="Red" BackColor="ControlLight">
                <asp:TextBox ID="Qty" runat="server"></asp:TextBox>
                 <asp:RequiredFieldValidator ID="WMCConQtyRFV" runat="server" ErrorMessage="***"  ControlToValidate="Qty" ValidationGroup="Add"></asp:RequiredFieldValidator>
            </asp:TableHeaderCell> 
           </asp:TableRow>





 <asp:TableRow ID="TableRow11" runat="server" ForeColor="Teal">

            <asp:TableHeaderCell BorderColor="Black" BorderWidth="1" BackColor="#0C0C25" ForeColor="White">Spare Part Serial Number :</asp:TableHeaderCell> 
            <asp:TableHeaderCell BorderColor="Black" BorderWidth="1" Width="200" HorizontalAlign="Left" BackColor="ControlLight">
                <asp:TextBox ID="WMCSerialNum" runat="server"  ForeColor="#0C0C25"></asp:TextBox>
            </asp:TableHeaderCell> 
            </asp:TableRow>



<asp:TableRow ID="TableRow16" runat="server" ForeColor="Teal">
            <asp:TableHeaderCell BorderColor="Black" BorderWidth="1" ColumnSpan="4" HorizontalAlign="Center" >
                <asp:Button ID="Add" runat="server" Text="Add" ValidationGroup="Add" OnClick="WMAdd_Click" />

            </asp:TableHeaderCell> 
        </asp:TableRow>

</asp:Table>



 <asp:Table ID="GridViewFE" runat="server"  ForeColor="Teal">
 <asp:TableRow ID="TableRow19" runat="server" ForeColor="Teal">
            <asp:TableHeaderCell BorderColor="Black" BorderWidth="1" ForeColor="BLACK" HorizontalAlign="Center" >

       <asp:GridView ID="GridView1" runat="server" OnRowDeleting="GridView1_RowDeleting" AutoGenerateDeleteButton="true">
         
       </asp:GridView>
         <asp:Button ID="Button1" runat="server" Text="Submit" OnClick="WMSubmit_Click" />
            </asp:TableHeaderCell> 
        </asp:TableRow>
        </asp:Table>



</asp:Content>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;


using System.Data;
using System.Collections;
using System.Configuration;
using System.Web.Security;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Text;
using System.IO;

namespace acmkweb.MM
{
    public partial class WebFormtest2 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

            if (!Page.IsPostBack)
            {
                FillContainerType();
            }

            ScriptManager scriptManager = ScriptManager.GetCurrent(this.Page);


        }




           private void FillContainerType()
        {
            Type.Items.Clear();

            string selectSQL = "SELECT CONTAINER_CODE,CONTAINER_TYPE,CONTAINER_DESC FROM [CIMProRPT01].[dbo].[WM_CONTAINERTYPE]";
          
            SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["CIMProRPT01ConnectionString"].ConnectionString);
            SqlCommand cmd = new SqlCommand(selectSQL, con);
            SqlDataReader reader;

            try
            {
                con.Open();
                reader = cmd.ExecuteReader();
               Type.Items.Add("--Select Type--");
                while (reader.Read())
                {
                    ListItem newItem = new ListItem();
                    newItem.Text = reader["CONTAINER_CODE"].ToString();
                    newItem.Value = reader["CONTAINER_CODE"].ToString();
                    Type.Items.Add(newItem);
                }
                reader.Close();
            }
            catch (Exception)
            {
               
            }
            finally
            {
                con.Close();
            }

        }





private void BindGrid(int rowcount)
       {
           DataTable dt = new DataTable();
           dt.Columns.Add(new System.Data.DataColumn("Type", typeof(String)));
           dt.Columns.Add(new System.Data.DataColumn("QUANTITY", typeof(String)));
           dt.Columns.Add(new System.Data.DataColumn("SparePartSerialNumber", typeof(String)));


           if (ViewState["CurrentData"] == null)
           {
               
               for (int i = 1; i <= rowcount; i++)
               {
                   string serialNumber = this.WMCSerialNum.Text.Trim();
                   string newSerialNumber = serialNumber.Substring(0, serialNumber.Length - 2);
                   dt.Rows.Add(Type.SelectedItem.Text, Qty.Text, newSerialNumber + (i).ToString());
                   //dt.Rows.Add(string.Empty, string.Empty, string.Empty);
               }

               GridView1.DataSource = dt;
               GridView1.DataBind();

               // Store the DataTable in ViewState to retain the values
               ViewState["CurrentData"] = dt;
           }
           else
           {
               dt = (DataTable)ViewState["CurrentData"];

               for (int i = 1; i <= rowcount; i++)
               {
                   string serialNumber = this.WMCSerialNum.Text.Trim();
                   string newSerialNumber = serialNumber.Substring(0, serialNumber.Length - 2);
                   //dt.Rows.Add(string.Empty, string.Empty, string.Empty);

                   dt.Rows.Add(Type.SelectedItem.Text, Qty.Text, newSerialNumber + (i).ToString());
               }
               GridView1.DataSource = dt;
               GridView1.DataBind();
               // Store the DataTable in ViewState to retain the values
               ViewState["CurrentData"] = dt;
           }
       




   }



          protected void WMAdd_Click(object sender, EventArgs e)
          {
              GridViewFE.Visible = true;

              int numbers = int.Parse(this.Qty.Text.Trim());

              string serialNumber = this.WMCSerialNum.Text.Trim();
              string newSerialNumber = serialNumber.Substring(0, serialNumber.Length - 2);

              this.BindGrid(numbers);

              //Here i am adding label if you dont want it then comment till end of for loop
              int cellCount = this.GridView1.Rows[0].Cells.Count;
              int rowsCount = this.GridView1.Rows.Count;

              Qty.Text = string.Empty;
              WMCSerialNum.Text = string.Empty;


              Qty.Focus();
              WMCSerialNum.Focus();


          }







        protected void WMSubmit_Click(object sender, EventArgs e)
        {


            foreach (GridViewRow oItem in GridView1.Rows)
            {
                string str1 = oItem.Cells[1].Text;
                string str2 = oItem.Cells[2].Text;
                string str3 = oItem.Cells[3].Text;
              



                insertData(str1, str2, str3);
            }

            Response.Redirect("WebFormTest.aspx?stat=insert");
        }



        public void insertData(string str1, string str2, string str3)
        {
            SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["CIMProRPT01ConnectionString"].ConnectionString);
            string sql = "INSERT INTO [CIMProRPT01].[dbo].[test] (test1,test2,test3) VALUES ('" + str1 + "','" + str2 + "','" + str3 + "')";

        

            con.Open();

            SqlCommand cmd = new SqlCommand(sql, con);



            cmd.ExecuteNonQuery();

            con.Close();


        }


        protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
        {

            DataTable dt = (DataTable)ViewState["CurrentData"];

            dt.Rows[e.RowIndex].Delete();

            GridView1.DataSource = dt;
            GridView1.DataBind();

        }




    }

}



    

Kindly advise, thank you