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.
['8057', '1169', 'M', '7475', 'n', '8081', '3217', 'q', 'V', '7225', 'f', 'l', '6829', 'A', '1031', 'z', '1225', '9859', '8671']