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.
['f', 'n', '5839', 'B', 'f', '6539', '9401', '8465', '5561', 'R', '5787', 'a', 'J', 'F', 'k', 'W', 'h', 'q', 'E', '8323']