In this task, you are given an input list A. You need to find all the elements of the list that are numbers and calculate their sum.
['9645', '9147', 'E', 'l', 'S', 'I', '277', 'f', '4727', '9349', '7169', '9747', 'J', '2735', '2893', 'L', '6751', '3203', '6419']