title: Check if number has a digit multiple times
body: <p>I've come across a puzzling challenge. I have to check if a number contains the same digit multiple times ex. 11, 424, 66 and so on. at first this seems easy enough but i'm having trouble coming up with a logic to check for this. any ideas?</p>
  
  <p>This is what I've got so far. the function takes in a list. (updated)</p>
  
  <pre><code>arr = [[1,20],[1,10]]
  
  for i in arr:
      l = list(range(i[0],i[1]))
      for num in l:
          if num &lt; 11: continue
          for c in str(num):
              if str(num).count(c) &gt; 1:
                  # dont know why code is popping off 12 and 13
                  print(l.pop(num))
  </code></pre>