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.
['3071', '355', 'e', '9781', 'R', '6833', 's', '2665', 'L', '9551', 'P', '6101', '2955', '4643', 'O', '3327', '2163', '685', '4277', 'B']