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: ['6921', 'a', 'U', '2821', '2111', 'h', '3937', '3697', 'd', '6309', 'q', '7961', '5287', '5375', '2721', '4523', 'V', '8633', 'c', '7643']

SOLUTION: 67939

PROBLEM: ['R', '3361', 'c', 'S', 'g', '3829', '7347', '6633', 'e', '9227']

SOLUTION: 30397

PROBLEM: ['4525', '5475', 'g', 'l', 'K', 'T', 'V', 'U', '8821', '8151']

SOLUTION:
26972