title: After String.Reverse, a mistake occurs in ToString
body: <p>When the application runs, the IDE tells me Input string is not in the correct format.</p>
  
  <pre><code>(Convert.ToInt32(_subStr.Reverse().ToString().Substring(4, _subStr.Length - 4))*1.6).ToString() 
  </code></pre>
  
  <p>I don't know how the <code>Reverse()</code> can be exactly used here.</p>