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.
['O', 'E', 'E', '4071', 'V', 'X', 'g', 'I', '4677', 'Y', 'N', '3711', 'O', '969', '2747', 'Y', 'j', 'v', '6251', 'V']