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: ['1391', '1719', '8547', 'x', 'a', 'j', '6395', 't', '3421', '6607', 'M', '1645', 'H', 'x', 't']

SOLUTION: 29725

PROBLEM: ['6161', 'p', '2839', 'c', '5905', '1729', 'j', '5901', '3013', 'e']

SOLUTION: 25548

PROBLEM: ['6591', 'H', '281', '7485', '4071', '9875', '2921', 'H', '9649']

SOLUTION:
40873