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.
['d', 'b', 'W', '3201', 'C', 'o', '5187', '9723', '8177', 'F', '6703', 'U', '1393', '1035', '3507', '5993', '3857', 'r', 'C', 'j']