title: Rails - Time arithmetic
body: <p>I was playing time arithmetic in rails console. I have subtracted two different times and got back a long number, please see below my code. </p>
  
  <pre><code>a = User.find(1).updated_at   # returns   Mon, 03 Mar 2014 11:07:43 UTC +00:00
  b = User.find(1).created_at   # returns   Mon, 03 Mar 2014 08:36:50 UTC +00:00 
  
  a - b                         # returns   9053.699814796448 
  </code></pre>
  
  <p>My question is. What is this number <code>9053.699814796448</code>? Is it time? What is it's unit? and how is that calculated? Is it possible to change the default unit of the outcome? </p>
  
  <p>Thanks </p>