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.
['c', 'y', '5235', 'A', '2241', 'S', 'o', 'V', '4985', '6955', 'k', '2895', 'Z', '2649', '4907', 'b', 'Q', 'b']