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.
['135', '6575', '4595', '3083', 'z', 'R', '4747', '8591', 's', 'B', 'h', '9555', '157', 'B', '819', 'e', 'I', '9739', '5167']