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.
['m', '1479', 's', '4693', 'V', '7715', 'u', 'Q', 'V', '6047', 'Q', 'i', '1119', 'v', 'Z', 'C', '8427', '3733', 'c']