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', '9189', '3691', '2869', '1525', 'd', 'H', 'P', '8613', 'b', 'r', '5289', 'V', '6433', '8733', 'K', '8105', '1041', 'U', 'L']