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.
['9445', '7291', 'r', 'g', '1175', '7823', '5507', 'j', '7249', '6335', '3853', 'b', 'u', 'S', '365', 'Z', '7489', 'S', 'W', 'e']