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.
['Q', '1853', '6445', 'O', '3865', 'v', '7907', 'O', 'x', '4921', '9455', 'Y', 'c', 'C', '7113', 'o', '4393', '4227']