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.
['2275', '3815', '2309', '803', 'c', 'b', 'y', 'n', '4421', '479', 'q', 'V', '6087', 'S', 'D', '5663', '2083', 'Z']