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: ['2787', 'z', '9351', '3339']
Example Output: 15477

Example Input: ['6367', '9923', '9141']
Example Output: 25431

Example Input: ['o', 'i', 't']
Example Output:
0