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.
['D', '8591', 'b', 'n', 'e', '883', '8923', '245', 'z', '5643', 'C', '2911', '9275', '711', '7299', '3449', '4799', '6065']