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.
['V', 'a', 'G', '5483', 'x', 'X', 'l', '8473', 'E', '5085', 'n', 'F', 'S', 'a', 'O', '4523', 'I', '2575', 'P', '1571']