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.
['Q', '9395', 'B', 'w', 'l', 'q', 'r', '9839', 'x', 'G', '5215', '6911', 'K', 'D', '8441', '5327', 'G', 'J']