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: ['6165', 'x', 'u', 'n', 'V', 'B', '4039', 'l', '991', 'x', '335', '9011', 'K', '8725', 'a', '6291', 'j']

SOLUTION: 35557

PROBLEM: ['r', '6537', '3001', '7879']

SOLUTION: 17417

PROBLEM: ['4995', 'q', 'q', 'P', '883']

SOLUTION:
5878