TASK DEFINITION: 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.
PROBLEM: ['X', 'P', 'x', '9471', '5', 'c', 'f', '5077', '1085', '2267', 'R', 'q', '4987', '9529', 'H', 'n', 'r', 'u']

SOLUTION: 32421

PROBLEM: ['B', '9189', '3691', '2869', '1525', 'd', 'H', 'P', '8613', 'b', 'r', '5289', 'V', '6433', '8733', 'K', '8105', '1041', 'U', 'L']

SOLUTION: 55488

PROBLEM: ['6233', 'Q', 'h', '3637', 'K', '1893', 'l', '6817', 'F', '945', 'p', 'q', 'w', '607', '1165', 't']

SOLUTION:
21297