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', '6537', '3001', '7879']
Example Output: 17417

Example Input: ['135', 'a', 'X', '8067', '8447', '4009', '4221', 'o', 'A', 'x']
Example Output: 24879

Example Input: ['w', '6503', '4791']
Example Output:
11294