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.
['Y', '1695', '5803', 'X', 'l', 'r', '6009', '1437', 'x', 'Q', '1629', 'E', '9575', 'k', '2069', '4345', 'z', '4417']