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

Example Input: ['1693', '9237', '7591', '1593', 'R', '6295', '9379']
Example Output: 35788

Example Input: ['1685', 'c', 'K', 'T', 'D', 'A', 'k', 'O', '1273', '99', '3581', '5353', '8715', 'S', '8917', 'P', '6447', 'O', 'X', 'Z']
Example Output:
36070