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.
['q', '6379', '1943', '1981', 'f', 'V', '6881', 'O', 'j', 'a', 'F', '8833', '3985', '9931', '3723', 'z', 'v', 'q']