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.
['G', 's', 'A', '3543', '2913', 'l', 'H', 's', '1607', '7099', '2679', '5897', '7013', '8567', '9111', 'c', '8531', 'e', 'r']