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: ['s', '425', '6135']

SOLUTION: 6560

PROBLEM: ['t', 'G', '217', 'W', 'l', 'j', 'd', 'U', '6795', '1609', 'n', '6919', '617', '5753']

SOLUTION: 21910

PROBLEM: ['1825', 'I', '687', '6537', 't', '5493', 'i', '2387', 'x', 't', '6753', '8817', '1869', 'f', 'a', '341', '5171', 'r', 'r']

SOLUTION:
39880