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.
['d', 'D', 'm', 'm', 'E', 'H', '4757', '2169', 'l', 'K', '7419', 'F', '5009', 'm', 'g', 'Q', 'L', 'F', 'z', '443']