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.
['9757', 'I', 'W', '1945', 't', '3293', '77', '4815', '8889', 'y', 'j', '4143', 'b', 'K', 'Y', 'e', 'h', 'F']