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.
['v', '507', 'V', 'q', 'i', 'e', '1945', '2009', '7705', 'n', 'D', 'u', '613', 'F', 'R', '6263', 'A', '4199', 's', 'k']