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.
['245', '4629', 'Q', 'b', '3933', '9931', '2343', 'Q', 'u', '3403', '6039', 'M', '5167', '7283', '8011', 'Q', '7089', 'B']