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.
['z', 'e', 'd', 'J', '549', '1803', 'Y', 'D', '4137', '2257', 'N', '8149', 'e', 'g', '1303', 'j', '925', '2845']