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.
['t', '7447', 'F', '507', '4431', 'L', '1629', '973', 'B', 'h', 'I', '9183', '9535', 'e', 'I', '3147', '6191', 'l', 'W']