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', 'F', '4477', '1565', '4407', 'r', 'v', '7237', '83', '5243', 'O', 'z', 'W', '7703', 'Q', 'i', '9657', 'n']
Example Output: 40372

Example Input: ['3839', 'D', '4741', 'L']
Example Output: 8580

Example Input: ['7901', 'q', 'w', 'F', '167', 'Z', 'F', '3373']
Example Output:
11441