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', '6189', '5435', 'y', '8931', '8987', 'F', '8377', 'k', '8631', '8717', 'q', '2923', 'g', '7225', 'j']

SOLUTION: 65415

PROBLEM: ['U', '9593', '2079', '5959', 'T', '5849', 'w', 'b', '9743', '6689', 'k', 'J']

SOLUTION: 39912

PROBLEM: ['E', 'B', 'a', '9781', 'J', 'z', 't']

SOLUTION:
9781