NonAction method within another action method

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace FiltersDemo.Controllers
{
    public class HomeController : Controller
    {
        [ActionName("Name")]
        public string StudentName()
        {
            return RollNumber();
        }
        
        [NonAction]
        public string RollNumber()
        {
            return "This is student Roll Number Method";
        }
    }
}