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.
['4509', '4165', '8651', '8057', 'a', '2241', 't', 'i', 'q', 'S', '5149', 'J', 'j', '1373', 'W', 'X', '235', 'm', '3225']