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: ['9787', '1491', '4411', '5261', 'U', '9787', 'b']

SOLUTION: 30737

PROBLEM: ['O', 'j', 'Z', 'u', '7427', '4225', '3139', '9993', '9945', '3639', 'h', 'j', 'f', '6511', 'e', '4607', '2741', '4743']

SOLUTION: 56970

PROBLEM: ['A', '351', '8029', 'K', '6269', 'x', 'h', 'j', 's', '8623', 'W', '5505', '2491']

SOLUTION:
31268