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.
['l', '9361', 'L', '1965', 'X', 'b', 'X', '7913', 'L', '541', '4701', 'Z', 'f', 'g', '3865', 'b', '1519', 's', '8013']