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: ['4811', 'Q', '2289', 'N', 'I', '7681', 'z', '8179', '3359', '5299', 'R', 'z', '8697', '5781', '4803', '2715', '6511', '1371']
Example Output: 61496

Example Input: ['W', 'c', 'P', '425', '4133', 's', '1831', '883', '2531', '681', 'U', 'B', 'H', '237', '4245']
Example Output: 14966

Example Input: ['5121', '999', 'M']
Example Output:
6120