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.
['w', 'V', '3359', '8847', '7551', '2481', 'Y', 'j', 'L', 'G', '7905', 'v', '4141', '2229', 'k', 'H', '3517', '3885', '3665', 'O']