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.
['k', '1477', 'W', '9049', '8615', 'x', '7301', '4361', '5525', '8879', 'T', '9551', 'M', '9579', '4443', '2869', 'y', 'o', '8163']