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.
['919', '6933', '5019', 'S', 'Y', '341', '3681', '1221', '9013', 'v', '769', 'X', 'F', 'T', 'x', '5745', '2755', '3559', 'N', 'L']