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.
['4645', '6939', 'h', 't', '6375', '3263', 'V', 'M', 'C', '8471', 'M', '1521', '1191', 'Y', 'e', '1643', '39', 'r', '9623', '9459']