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.
['E', 'Z', '1757', 'o', 'M', 'R', '6985', '4063', 'l', 'C', '7745', 'M', '3905', '5467', 'w', 'p', '3761', '5641', '9509', 'l']