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.
['z', '6859', '9003', 'Y', '303', '2887', 'x', '7649', '8695', '2517', '9247', 'o', 's', '259', 'n', 'S', '8267', 'q', 'n']