title: how to find upside down of a 2digit number
body: <p>I am trying to write program to find upside down of all double digit number. Actually I have written this code and it works pretty well too.  Any other alternatives to find upside down of an integer. Say 18=81 and 96=69....</p>
  
  <pre><code>List &lt; Integer &gt; al = new ArrayList &lt; Integer &gt; ();
  
  al.add(10);al.add(11);al.add(16);al.add(18);al.add(19);al.add(60);al.add(61);
  al.add(66);al.add(69);al.add(80);al.add(81);al.add(86);al.add(88);al.add(91);
  al.add(96);al.add(98);al.add(99);
  
  Scanner s = new Scanner(System.in);
  Integer n = s.nextInt();
  if (((String)"" + n).length() == 2) {
      if (al.contains(n))
          System.out.println("yes");
      else
          System.out.println("no");
  }
  </code></pre>