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: ['P', '237', 'X', '8893', '7931', 'F', '8359', 'S', '6931', '6953', 'r']
Example Output: 39304

Example Input: ['3469', 'n', '5561', '8597', '921', '4737', 'r', 'P', '7127', '3651', 'D', '1703', 'y']
Example Output: 35766

Example Input: ['i', '7405']
Example Output:
7405