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.
['k', 'v', '4021', 'X', '3297', '8101', '6789', '5399', '8881', '227', 'G', 'P', 'O', '5979', '7939', '8645', '7561', '5545', '9127']