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.
['8789', 't', '1421', '6389', '9427', '6139', 'x', '9347', 'E', 'e', 'c', '3685', '9031', '4169', '3223', '479', '4519', '5373', '4711', 'H']