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.
['4881', '4655', 'y', 'E', '7093', '7623', 'x', '3707', '7175', 'Z', 't', '2313', '4025', '473', 'f', 'Z', '3579', '6929', 'N', 'S']