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.
['F', 'v', 'G', '6023', 'M', 'Q', 'A', '8477', '2079', 'A', '813', 'C', '3479', 'G', '1977', '5569', '8749', 'Y']