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.
['f', 'F', 'E', '2279', 'r', '6419', 'd', 'M', '3975', '3797', '9201', 'F', 'c', '4753', '959', 'v', '8963', '4007']