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.
['1505', 'e', 'q', '1319', 'w', 'y', 'O', '7409', 'e', 'u', '9901', 'F', '5467', 'B', '9423', '1643', 'u']