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.
['3381', '1261', '5717', '5933', '7155', '1831', '8299', 't', 'O', '3611', 'F', '1025', 'D', '9685', '5483', 'Q', 'y', '7597']