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.
['i', 'J', 'b', 'Z', 'b', '9389', 'T', 'H', 'l', 'Z', 'd', '1023', 'A', 'n', '6829', 'n', 'G', 'h', '8297']