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.
['p', 'q', 'R', '9871', 'R', '2237', 'G', 'D', 'a', '3047', 'd', '5213', '2429', '2559', 'Z', '2373', 's', '1677', 'R']