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.
['8383', 'W', '5733', 'L', 'C', '4297', 'e', '4885', 'Y', 'I', 'B', 'y', 't', 'n', 'D', 'V', 'c', 'r', 'W']