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: ['R', 'I', 'f', 'K', 'p', '8579', 'e', '1223', 'I', 'K', '8311', '2147', '4241', 'z', '6671', 'r']
Example Output: 31172

Example Input: ['c', 'd']
Example Output: 0

Example Input: ['O', 'g', '7415', 'k', '1405', 'Y', 'u', '2567', 't']
Example Output:
11387