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.
['Q', 'b', '2211', '8137', 'H', 'G', 'O', 'V', '7005', '9487', 'a', '7931', '4655', '2827', 'l', 's', '6825', '6739']