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.
['e', '4243', '1703', '3227', '3123', 'c', 'L', '9553', '9295', '9181', '1983', 'k', 'k', '571', '7409', '3373', '3785', '6031', 'g']