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.
['W', '6169', '8635', 'a', 'W', '899', 'r', 'w', 'J', 'y', '8459', 'n', 'L', 's', 'Z', 'x', 'd', 'J', '6133']