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.
['c', '7061', '3815', 'N', '5837', '6275', '3907', '8949', '6399', '1879', '5995', 'h', 'Y', '8329', 'q', 'n', 'n', '5061', 'a']