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.
['y', '8755', '3147', '8985', 'H', '8349', 'U', 'O', '7153', '7051', '9313', 'f', '4303', '2627', '7555', 'E', 'x', '5809', '6469']