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: ['3331', '5791', 'r', 'Q', '2243', '8229']
Example Output: 19594

Example Input: ['4515', '3911', 'M', 'T', 'w', 'F']
Example Output: 8426

Example Input: ['U', 'O', 'N', 'J', 'g', '7579', '8005', '8887', 'L', 'X', '9793']
Example Output:
34264