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.
['c', 'q', 'm', 'M', '501', '5851', 'k', '973', 'g', 'i', 'z', 'M', 'J', 'W', 'O', '2299', 'C', '9701', '839', 'E']