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: ['2683', '4431']
Example Output: 7114

Example Input: ['S', 'D', '3101', '4967', '8197', '5025', '4257', 'S', 'X', '7641', 'n', '6775', '4719', 'o', '2821', 'x', '5605', '2181']
Example Output: 55289

Example Input: ['t', '6867', '9917', 'e']
Example Output:
16784