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: ['x', 'd', '5121', 'I', '6737', '3789', '6167', 'C', '8947', 'k', '4715', '1885', 'H', 'B', '5685', 'S', '4615', 's', '7709']

SOLUTION: 55370

PROBLEM: ['3839', 'D', '4741', 'L']

SOLUTION: 8580

PROBLEM: ['d', '353', '851', 'b']

SOLUTION:
1204