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.
['9675', 'G', '9907', 'M', '9843', 'm', '2017', '3993', '7237', 'B', '9373', 'D', 'o', '8265', 'y', '6689', 'W', '5787', '4597']