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.
['9289', 'T', 't', 'V', '4641', '2345', '4905', 'o', 'c', 's', '9713', '3173', 'Z', 'a', 'k', '9989', 'V', 'g', 's']