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.
['X', '43', '2151', 'v', '5385', 'l', 'B', '6611', '9063', '621', '7379', 'P', 'C', '1503', 'e', 'D', 'u', '4861', '9987', '6015']