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.
['W', 'O', 'c', 'r', 'E', 'w', '9811', '6421', '3543', '4293', '8255', 't', '229', '745', 'w', 'p', '6861', '5305', 'h']