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.
['B', '7485', 'o', '9571', '5639', 'o', '3723', 'H', '2505', 'G', '97', '249', '8309', 'x', 'M', 'V', '2549', '5807', '9551', '3049']