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.
['V', 'M', '3995', '3133', '7907', '7979', '3649', '6261', '6143', 'p', '5953', 'J', 'e', '9359', 'a', '5787', '6809', 'Q']