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.
['4855', '4701', '3257', 'N', '9923', 'e', '7013', '161', '7573', '4745', '79', 'q', 'e', '1413', 'T', '1865', '6343', '2799', 'V', '1491']