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.
['231', 'U', 'c', '2395', 'I', 'x', '3855', 'o', '4739', 'l', 'z', '2089', 'C', '673', 'm', '4515', 'h', '131', 'E', '4951']