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.
['1429', 's', 'T', '6199', 'D', '9303', '2571', 'N', '8797', '5671', 'r', '6051', '3947', 'G', '8961', 'k', 'l', '9245']