title: Given a list of numbers, find a fix range that can cover the most numbers
body: <p>in python, we can use counter to find the most common element in a list.
  Is there a way we can pass in the function, so that we can counter the element that falls in certain range.</p>
  
  <p>Say I have [123, 127, 99,75,86, 83,81], I want to return the something like {'12X':2, '8X':3, '99':1, '75':1}</p>
  
  <p>Any ideas?</p>