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.
['453', 'L', '9161', '947', '3383', 'R', 'N', 'K', '5033', 'K', '2119', 'o', 'p', 'J', 's', 'I', 'e', 'a', '1213']