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.
['E', '8271', 'g', 'k', '421', '7493', 'K', 'W', '8367', 's', '1059', 'g', '9103', 'D', '185', 'r', '4779', 'T']