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.
['f', 'H', 'J', '6353', '5613', 'Q', '629', 'R', '7125', 'Q', 'o', '1383', '3383', '1863', '43', '4701', 'm', 'a', 'A']