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.
['J', 'j', '9357', 'v', '4061', '4429', 'P', 'l', '8755', 'v', '9605', '8213', 'J', '8191', 'G', '9571', 'L', 'c', 'R', 'H']