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.
['8311', '3565', 'h', 'A', 'K', '821', 'p', '3117', 'o', '9699', '4501', '1009', 'L', 'k', '9533', 'm', '7175', '6411']