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.
['6563', 'R', 'M', 'B', 'b', 'E', '9911', '7327', 'J', '7389', 'w', 'b', 'c', '1527', 'K', 'r', '5441', '6823', '8455']