title: What is the syntax to accept only numbers and ignore any extra signs like "%" as user input?
body: <p>I am using Python 3. I want the user to input the interest and I know that they will answer it with a <code>%</code> symbol following it.</p>
  
  <p>My current syntax is:</p>
  
  <pre><code>interest = input ('Enter the interest ')
  </code></pre>
  
  <p>(Does using <code>raw_input</code> help? It didn't even work somehow.)</p>