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.
['o', 'V', '8119', '3557', 'B', 'C', '1343', 'c', '9165', 'z', 'b', '4155', '6485', 'K', '1321', 'g', 'U', '4397', 'W']