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.
['2805', '1449', '435', '9869', '8751', 'g', 'f', 'a', 'E', '3669', 'V', 'Y', '5735', 'A', '6311', 'N', 'g', 'g', 'X']