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.
['B', 'U', 'v', '7823', '8953', '4513', 's', 'H', 'e', '2805', 'Y', 's', '3917', '8893', 'i', 'u', '7131', 'x', 'k', '9367']