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: ['d', '7305', '8903', 'b', '7687', '6393', '6939']
Example Output: 37227

Example Input: ['9403', 'u', '4159', 'w', '3467']
Example Output: 17029

Example Input: ['X', 'f', 'p', 'R', 'N']
Example Output:
0