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', 'J', 'z', 'o', '1121', '7247', '8987', 'u']
Example Output: 17355

Example Input: ['f', 'N', '8597', 't', 'K', '9755', 'j', '9747', '7259', '5493', 'n', '7269', '8493', '2279', '5369', 'f']
Example Output: 64261

Example Input: ['2213', '6021', '169']
Example Output:
8403