<script type="text/javascript">
    var count;

    function GetResult() {
        if (count <= <%= Total %>) {
            $.ajax({
                type: "POST",
                contentType: "application/json; charset=utf-8",
                url: "Default.aspx/GetResult",
                data: "{'value': '" + count + "'}",
                dataType: "json",
                async: false,
                success: function (result) {
                    var txt = $("#txt");
                    txt.html(txt.html() + "</br>" + result.d);
                    count++;
                }
            });
        }
        return false;
    }

    $(document).ready(function () {
        count = 1;
        for (var i = 0; i < <%= Total %>; i++) {
            setTimeout(function(){ GetResult(); }, i * 500); 
        }
    });
</script>

public partial class Default : System.Web.UI.Page
{
    public int Total { get { return 10; } }

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            Enumerable.Range(1, Total).ToList().ForEach((d) => Session["ID_" + d] = d * 100);
        }
    }

    [WebMethod]
    public static int GetResult(int value)
    {
        var obj = HttpContext.Current.Session["ID_" + value.ToString()];
        return Convert.ToInt32(obj);
    }
}