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.
['7913', '4149', 'K', 'Y', '1085', '1487', 'H', '9803', 'x', '1881', 'J', '6291', 'd', 'K', 'o', '8079', '613', '1889']