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: ['d', '7305', '8903', 'b', '7687', '6393', '6939']

SOLUTION: 37227

PROBLEM: ['r', '2251', 'X', 'H', 'a', '5463', 'g', 'M', '9797', '1581', 'o', 'm', 'v', 'E']

SOLUTION: 19092

PROBLEM: ['U', 'q', '7273', '7079', '6691']

SOLUTION:
21043