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.
['8687', 'U', '1083', 'g', 'q', '6291', '7243', 'T', '7929', 'Y', '9603', 'r', '8051', '8629', 'E', '9895', '8713', '8823', 'x']