title: how to save xls file as xlsx file using NPOI c#?
body: <p>I'm using NPOI to open <strong>XLS</strong> file, then add some modifications to the XLS file.
  at the end i want to save it as <strong>XLSX</strong> file.  </p>
  
  <p>i'm using this code to save it as XLS file:                                          </p>
  
  <pre><code>using (var fs = new FileStream(Name, FileMode.Create, FileAccess.Write))
  {
       wb.Write(fs);
  } 
  </code></pre>
  
  <p>Is it possible to save this <strong>XLS file as XLSX file</strong> using <strong>NPOI</strong> in <strong>C#</strong>?</p>
  
  <p>Thanks in advance for your response</p>