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.
['3325', '6661', '2045', 't', '5117', 'V', '309', 'a', 'd', '2913', '9371', 'j', 's', 'a', 'z', '7357', '5315', '5763']