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.
['9087', 'l', '3439', '8889', '8975', '4751', '7047', 'b', 'W', 'R', '8935', 'u', '8569', '2833', '5999', 'o', 'H']