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.
['9213', '5883', '4251', '6697', 'K', 'S', '1297', 'K', 'a', '9239', 'm', '4967', '9743', 'J', 'o', 'y', '9861', 'D', 'e', 'u']