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.
['8197', 'h', 't', 'P', 'I', 'S', '4917', 'J', '965', '1499', '6309', 'Y', '5949', '1063', 'A', '1973', 'u', 'K']