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.
['1815', 'e', '5415', '8865', '7741', 'E', 'h', 'h', 'E', '6761', '4919', 'G', '1099', 'n', 'X', 'Q', 'h']