title: dividing a number by a string that contains a value?
body: <p><br/>
  I define, let's say, <code>E=10</code> the I try to do <code>A=1/E</code> (in python), then python tells me :</p>
  
  <p><code>TypeError: unsupported operand type(s) for /: 'int' and 'str'</code><br/></p>
  
  <p>How should I do this please?<br/></p>
  
  <p>Thanks !</p>