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.

Example Input: ['r', '3537', 'T', '3611', 'k', '4983', 'h', '4317', '8727', 'E', '6471', '8465', 'f', '5429', 'T', '2169', '2171', 'P', '6941', 'D']
Example Output: 56821

Example Input: ['c', 'd']
Example Output: 0

Example Input: ['4975', 'M', 'C', 'D', 't', 'i', 't', 'L']
Example Output:
4975