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.
['W', 'm', '713', '1423', 'd', 'N', '9675', 'g', 'z', '8877', 'U', '2099', '3401', 'x', '3685', 'k', 'V', '9833']