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: ['2087', '8171', 'c', 'd', 'a', '5621', 'n']
Example Output: 15879

Example Input: ['6347', '5495', '169', '9503', 'H', '571', '6105', 'X', 'r', 'e', '7369', 'a', 'd', '6999']
Example Output: 42558

Example Input: ['L', '6395']
Example Output:
6395