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: ['m', 'g', '7251', '5873', '59', '7345']
Example Output: 20528

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

Example Input: ['x', '4901', 'f', '1103', 'B', '487', 'Z', 'D', 'N', '4619', 'f', 'P', '7403']
Example Output:
18513