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.
['m', '5459', 'E', 'V', '4625', 'R', '6649', 'l', '5111', '4873', '6351', '9467', '9245', '1509', 'b', '8913', '5647', '9405', '9335']