[DefaultMemberAttribute("Item")] 
[SerializableAttribute()] 
public class OrderCollection : System.Collections.ObjectModel.Collection<Order> 

class MyPage : System.Web.UI.Page
{
   private int NumPages(ref Dynamicweb.eCommerce.Orders.OrderCollection Orders, ref Dynamicweb.eCommerce.CustomerCenter.CustomerCenterSettings Settings)
   {
       int pageSize = Settings.ItemsPerPage;

       int ret = 0;
       ret = Convert.ToInt32(Orders.Count / pageSize);
       if ((ret * pageSize) < Orders.Count)
       {
           ret += 1;
       }
       return ret;
   }
}