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: ['R', 'C', 'S', 'x', '1529', 'r']
Example Output: 1529

Example Input: ['U', '5885', 'u', 'Y', 's', 'w', 'j', '9629', '9505', 'U']
Example Output: 25019

Example Input: ['2937', '4513', 'O', 'm', 's']
Example Output:
7450