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.
['C', '3055', 'I', 'l', 'f', 'r', '6957', '8051', 'e', '2347', 'P', '3481', '9177', '3605', 'Z', '3397', '173', 'C']