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.
['3039', '6455', '7105', '5301', '247', '5419', 'C', '7731', 'Z', '6891', '1795', '4345', 'f', '6301', '139', '9057', '8497', 'h', '8399']