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: ['c', '7415', '6253', '4477', 't', '9449', '7733', '2325', 'Z', '5413', 'q', 'm', 'R', '8619', '7289', '857', '7273', '7425']
Example Output: 74528

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

Example Input: ['9269', '7991', 'k', '3039', 'y', '7029', 'P']
Example Output:
27328