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.
['P', '5363', 'k', '8045', 'R', 'r', 'm', '2103', 'u', '1129', '2595', '8097', '2311', 'G', 'Z', 'E', '4649', 'y']