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.
['A', 't', 'K', 'o', '7971', '2567', 'S', '379', 'd', 'e', 'K', '1919', '6869', '2917', 'G', '4147', 'j', '2063', '9737']