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: ['2325', '3259', '1947', '8065', 'H', '2329', 'h', 'l', 'k', 'R']
Example Output: 17925

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

Example Input: ['5451', 'e', '831', 'U', 'K', 'O']
Example Output:
6282