Global.asax.cs

using System;
using System.Web.Http;
using System.Web.Routing;

namespace CalculatorWeb
{
    public class Global : System.Web.HttpApplication
    {

        protected void Application_Start(object sender, EventArgs e)
        {
            RouteTable.Routes.MapHttpRoute(
            name: "CalculatorApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = System.Web.Http.RouteParameter.Optional }
        );
        }

        protected void Session_Start(object sender, EventArgs e)
        {

        }

        protected void Application_BeginRequest(object sender, EventArgs e)
        {

        }

        protected void Application_AuthenticateRequest(object sender, EventArgs e)
        {

        }

        protected void Application_Error(object sender, EventArgs e)
        {

        }

        protected void Session_End(object sender, EventArgs e)
        {

        }

        protected void Application_End(object sender, EventArgs e)
        {

        }
    }
}