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.
['4045', 'P', 'J', '8693', 'R', 'J', '6793', 'a', '8969', '4547', '5331', '8541', 'g', 'k', 'm', 'D', 'Z', 'E', '365', '7397']