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: ['3629', '8785', '9537', '8479', '3523', 'c', 'C', '5093', '2405', 'y', '1145', '8987', 'f']
Example Output: 51583

Example Input: ['5979', '3577', '1039', 'M', '803', '5287', 'B', '4555', 'l', '1211', '5517', 'b']
Example Output:
27968