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', 'd', '9401', '7043', 'f', 'h', 'q', 'u', 'c', 'q', 'k', '4297', '8201', '3243', '225', 'C', 'm', 'N']