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.
['5595', 'b', '8093', 'm', 'Z', 'X', 'k', '3709', 'K', 'a', 'g', 'g', 'a', '4889', '9675', 'k', 'O', 'g', '4025']