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: ['2729', 'W', 'i', '9073', '343', 'j', '2329', '9159', '4825']
Example Output: 28458

Example Input: ['7669', '3367', 'A', 'Z', '6173', '4391', 'f', 'S', '9657', '2631']
Example Output: 33888

Example Input: ['S', 'y']
Example Output:
0