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.
['E', '2351', '7587', '2591', '5017', '2261', 'W', '6011', 'H', '6931', '639', '6621', 'n', '9837', 'W', '85', 'v', '9853', '311']