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: ['k', 'a']
Example Output: 0

Example Input: ['2913', 'b', 'j', '7591', 'O', 's', '5589', '4995', '7503', 'U', 'S', 'C', '6797']
Example Output: 35388

Example Input: ['8543', '8581', '415', 'X', '443', '1223', '8775', '3933', 'k', '3265', 'Z']
Example Output:
35178