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: ['K', '4403', 'a', '3881', '4139', 'w', '1861', 'G']
Example Output: 14284

Example Input: ['Y', '263', '641', '1163', 'p', 'r', 'L', '4425', 'C', '7585']
Example Output: 14077

Example Input: ['l', 'y', '1339', '2117', '7487']
Example Output:
10943