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: ['q', 'N', 'y', '7859', 'u', '2861', '4151', 'Q', 'x']

SOLUTION: 14871

PROBLEM: ['4425', 'x', '1959', 'C', 'c', 'D', 'M', '8317', 'q', 'x', '4277', 'N', 'z', 'I', '1921', 'o', 't']

SOLUTION: 20899

PROBLEM: ['1967', '1421', 'E', 'C', 's', 'N', '7821', 'u']

SOLUTION:
11209