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.
['6035', '6977', '5223', '2929', '2235', 'F', '7851', '4733', '4595', 'm', 'R', '2619', '1499', '5365', 'l', '1217', '3319', 'E', '4269']