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: ['3433', '6955', 'Q', 'E', '3557', 'S', '2931', '9879', 'S', 'f', 'Q']
Example Output: 26755

Example Input: ['X', 'u', 'B', '269', '9089', 'M', '5175', 'K']
Example Output: 14533

Example Input: ['821', 'D', 'n', 'v']
Example Output:
821