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.
['q', 'k', '1375', 'i', 'k', '3751', '9879', '353', '3753', '6161', '8651', 'X', '5949', 'x', '4683', '9117', 'O', 'Q', '9817']