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.
['9639', '7795', '5841', '6559', 'C', 'V', 'j', '8755', 'C', '4899', 'h', '4755', 'G', 'E', '9289', '7197', 'W', 'b', 'R']