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', '9625', 'K', 'L', 'v', 'c', 'A', '567', '269', 'W', '5105', '6945', 'K', 'z', 'a', 'q', 'O', '1775']