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.
['3947', 'F', 'V', 'M', '7843', '4525', 'Y', '8571', 'O', 'D', '3285', '1065', 'f', '5191', 'G', '317', 'x', 'd']