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', 'c', 'H', 'd', '241', '4357', '4587', 'S', 'L', 'j', 'y', 'x', 'l', '6321', 'P', 'b', 'o', 'C']