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.
['5259', 'v', 'L', '823', 'o', 'g', '3713', 'Z', 'v', 'a', '7229', '6691', 'k', '5975', 'O', 'v', 'v', '477', '2625', 'F']