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.
['2901', 'T', 'Z', '8335', 'E', '7885', 'Y', 'O', 'I', '4377', 'H', 'U', '8667', 'K', 's', 'X', '6587', 'F']