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.
['N', 'j', 'p', '9989', 'z', '8547', '2575', '2789', 'j', '4569', 'C', 'X', '1463', '4563', '5989', '689', 'd', 't', '1765', '1795']