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.
['6833', 'R', '7323', 'd', '3487', '8777', '9053', 'y', 'i', 'O', '467', 'b', '5969', 'D', 'B', 'r', '3073', 'i', 't', 'd']