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.
['9401', 'o', '1451', '8875', 'j', '87', 'U', 'L', '7305', '2233', 'Z', 'v', '7245', 'f', '4653', '9021', 'i', '9517']