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', 'X', 'k', 'v', 'h', 'l', 'Y', '1691', 'I', 'S', 'S', '3325', '9849', 'K', 'G', '7275', 'S', 'I']