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: ['3433', '6955', 'Q', 'E', '3557', 'S', '2931', '9879', 'S', 'f', 'Q']
Example Output: 26755

Example Input: ['d', '4553']
Example Output: 4553

Example Input: ['n', 'B', '3841', '1551', '7221']
Example Output:
12613