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.
['9855', '6233', 'A', 'E', '8729', '4495', 'q', 'U', '3347', 'e', '989', 'Y', '7747', 'D', 'd', '157', 'T', 'W']