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.
['T', 'a', 'h', '3843', 'D', 'i', '5417', 'e', '8615', 'Z', '1257', 's', 's', 's', 'T', '7225', '9667', 'y', '1771', 'A']