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: ['I', '7815']
Example Output: 7815

Example Input: ['P', '6161', 'k', '5925', 'h', 'G', 'n']
Example Output: 12086

Example Input: ['W', '9225', 'W', '3467', '9685', 'n', '6617', 'O', '9225', '4637', '3223', 'm', 'I', 'E', 'T', '5363', '4229', '3991', 'u']
Example Output:
59662