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.
['m', '6263', 'G', 't', 'X', '5889', 'H', '917', '4211', '9707', '6389', 'K', 'L', '1495', 'C', 'v', 'y', '6575', 't']