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.
['v', 'I', 'a', 'i', '2373', '5405', '7409', '5777', 'i', '137', '4625', '365', '4701', 'Y', 'g', '8955', 'W', '3617', 'P', 'C']