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.

['X', '989', 'U', '9551', '6385', 'Y', '1433', 'J', '1833', '685', 'u']
20876

['4869', 'L']
4869

['7841', 'J']

7841