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.
['7283', 't', '6743', 'q', 'w', '465', '7289', '5053', '3443', 'p', '941', '837', '2597', 'o', '5353', '81', 'I', 'v', 'j', 'B']