title: Server Error in '/' Application MVC5
body: <pre><code> CalculatorController
          public class CalculatorController : Controller
          {
              // GET: Calculator
              [HttpPost]
              public ActionResult Index1(double a, double b, string op="+")
              {
                  switch(op)
                  {
                      case "+":
                          ViewBag.Ketqua = a + b;break;
                      case "-":
                          ViewBag.Ketqua = a + b;break;
                      case "*":
                          ViewBag.Ketqua = a + b;break;
                      case "/":
                          ViewBag.Ketqua = a + b;break;
                  }
                  return View();
              }
          }
  </code></pre>
  
  <p>Index1 View</p>
  
  <pre><code>@{
      ViewBag.Title = "Index1";
  }
  
  &lt;h2&gt;Index1&lt;/h2&gt;
  &lt;form name="formcalculator" action="/Calculator/Index1" method="post"&gt;
      &lt;div&gt;
          Nhập a: &lt;input type="text" name="a" size="20" /&gt;
          &lt;br /&gt;
          Nhập b: &lt;input type="text" name="b" size="20" /&gt;
          &lt;br /&gt;
          &lt;input type="radio" name="op" value="+" /&gt; +
          &lt;input type="radio" name="op" value="-" /&gt; -
          &lt;input type="radio" name="op" value="*" /&gt; *
          &lt;input type="radio" name="op" value="/" /&gt; /
      &lt;/div&gt;
      &lt;div&gt;
          &lt;input type="submit" value="Calculator" name="btnOK" /&gt;
          @ViewBag.Ketqua
      &lt;/div&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>URL: <a href="http://localhost:1524/Calculator/Index1" rel="nofollow">http://localhost:1524/Calculator/Index1</a>
  but</p>
  
  <pre><code>Server Error in '/' Application.
  </code></pre>
  
  <p>The resource cannot be found.</p>
  
  <p>Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable.  Please review the following URL and make sure that it is spelled correctly. </p>
  
  <p>Requested URL: /Calculator/Index1</p>
  
  <p>Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34274</p>