title: 12345.class returning 'Integer' not 'Fixnum' in Ruby
body: <p>On the Ruby tutorials I'm watching when you enter a number with <code>.class</code> it returns either <code>Bignum</code> or <code>Fixnum</code>.</p>
  
  <p>When I do this I get <code>Integer</code> instead:</p>
  
  <pre><code>12345.class
  #=&gt; Integer
  </code></pre>
  
  <p>I'm using irb in the command line on a mac.  Why does the above not return <code>Fixnum</code> like it does in the tutorials?</p>