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.
['n', '2275', '8021', '247', 'H', 'E', '9307', '8703', '457', 'h', 'f', '4463', 'Z', 'O', '2167', 'G', 'O', '9385', '1199', 'n']