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.
['855', 'g', '8081', 'G', '3253', '9971', 'x', '7613', '1295', '6825', '2187', '7339', 'n', '589', '3955', 'b', 'd', 'q', '4119', '1435']