title: Generate x+xx+xxx+xxxx ... for a given integer (for 4 -> 4+44+444...)
body: <p>I have to incrementally concatenate a given number on each iteration so that it returns a sum and the concatenated string. This is my try:</p>
  
  <pre><code>def digit_sum_from_letters(x):
      a = int("%s" % x)
      b = int("%s%s" % (x,x))
      c = int("%s%s%s" % (x,x,x))
      d = int("%s%s%s%s" % (x,x,x,x))
      return a+b+c+d
  print digit_sum_from_letters(9) 
  </code></pre>
  
  <p>returning <code>11106</code></p>
  
  <p>But I need to generate the sum for whatever given integer so I need a loop but I'm stuck.</p>
  
  <p>Thanks!</p>