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: ['A', '771', 'Q', 'b', '9929', '4991', 'q', '9863', '4363', '5721', 'C', '991', 'j', 'r', 'Q', 'B', 'K']

SOLUTION: 36629

PROBLEM: ['R', '7947', '7717', 'J', '2849', 'j', 'K', 'z', '1071', '9827']

SOLUTION:
29411