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.
['U', '9319', '7409', '9939', '1433', '3419', '6001', '8157', '8897', 'P', '809', '1503', '2937', '6745', 'h', 'B', 'Z', '2369']