title: regex starting with number 5
body: <p>looking for help applying a regex function that finds a string that starts with 5 and is 7 digits long.</p>
  
  <p>this is what i have so far based on my searches but doesn't work:</p>
  
  <pre><code>import re
  
  string = "234324, 5604020, 45309, 45, 55, 5102903"
  re.findall(r'^5[0-9]\d{5}', string)
  </code></pre>
  
  <p>not sure what i'm missing.</p>
  
  <p>thanks</p>