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.
['2085', '8859', '509', '9519', 'x', 'A', 'S', 'H', 'U', 'b', 'b', 's', '8531', 'S', 'O', 'g', 'Z', 'O']