title: Python/Pandas subtracting numbers in a column
body: <p>Sorry if this is a dumb question,</p>
  
  <p>I have a pandas data frame that looks kind of like this:</p>
  
  <pre><code>Col1   Col2
  
  0      217
  287    130
  </code></pre>
  
  <p>I'm trying to subtract the two numbers inside column 2</p>