title: Python: Using lower function on tuples
body: <p>I'm new to Python and have looked at quite a bit of documentation to figure out what is going on, but haven't had any luck. </p>
  
  <p>I have a list of tuples that I need to convert to lowercase and perform mathematical operations on all values in the list. The "E", needs to become an "e" in order to perform mathematical operations.  </p>
  
  <p>If there is a single value in a given list of tuples, the following works: </p>
  
  <pre><code>EarthU = ['1.3719107E+11', '8.3311764E-02', '2.2719107E+11', '1.4880643E+03']
  earthU = [element.lower() for element in EarthU]
  earthU = [(0.3048*0.3048)*float(element) for element in earthU]
  </code></pre>
  
  <p>If there are more than one value for each tuple in a given list of tuples and I try the same logic: </p>
  
  <pre><code>EarthV = [('4.2997980E+12', '7.5608735E+13'), (1.8986931E+00', '3.0367303E+02'), ('3.4997980E+12', '7.5608735E+13'), ('-4.9202352E+04', '2.8277192E+06')]
  earthV = [element.lower() for element in EarthV]
  </code></pre>
  
  <p>And I receive the following error when trying to convert each element in the tuple to lowercase: </p>
  
  <blockquote>
    <p>AttributeError: 'tuple' object has no attribute 'lower'</p>
  </blockquote>
  
  <p>I have a feeling that this attribute error I am running into will become a problem when I try to perform the mathematical operations as well. 
  Thanks.</p>