title: In php substr(INFORMATICS&SYSTEMS-58600,-5) is returning 'ATICS'
body: <p>I know this type of questions have been asked before but none solves my problem.</p>
  
  <ol>
  <li>I want to capture numeric parts of this string <code>INFORMATICS&amp;SYSTEMS-58600</code> i.e. <code>58600</code>. </li>
  <li>I am trying to do <code>substr(INFORMATICS&amp;SYSTEMS-58600,-5)</code> which returns <code>ATICS</code> which is substr of first part of string <code>INFORMATICS</code> but I want the last part.</li>
  <li>Wherever &amp; is appearing this is behaving same.</li>
  </ol>
  
  <p>I know its a very basic  mistake but what ??? I cant figure out.Please help me out.</p>