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: ['P', '237', 'X', '8893', '7931', 'F', '8359', 'S', '6931', '6953', 'r']
Example Output: 39304

Example Input: ['4177', 'd', 'b', 'm', 'f', 'R', '797', '7905', '4355', '7515', '9801', 'F', 'R', '9125', '8445', 'k', 'K', 'K']
Example Output: 52120

Example Input: ['z', 'Q', '7797', 'B', '9377', '7645', 'L', 't', '3639', 'W', '5185']
Example Output:
33643