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.
['D', 'C', '7295', 'g', 'j', '1387', 'O', '4701', 'B', 'd', 'W', 'b', 's', 'n', 'n', '4917', '2941', '1825', 'x']