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.
['g', 'x', '3591', 'm', '4345', 'C', 'K', '7159', '3697', '1957', '3041', 'J', '6913', 'E', '8913', '3919', '6743', 'A', 'x', '9807']