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.
['x', '6053', '1573', 'B', 'n', 'O', 'z', '1761', '6121', 'x', '4293', 'z', 'h', '9743', '8827', '873', 'd', '8247', 'C']