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.
['2383', 'C', '7273', 'X', 'O', 'i', 'a', '2379', 'V', 'P', 'p', 'p', 'F', 'u', '8915', 'Y', 'c', 'a']