title: Return minutes in DateTime subtraction
body: <p>The following returns <code>(5/12)</code>, a <code>Rational</code> object.</p>
  
  <pre><code>d = DateTime.current
  d2 = d + 10.hours
  d2 - d
  </code></pre>
  
  <p>How would I get the minute difference from the two points in time?</p>