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.
['729', 'I', '6847', '6257', '3239', '9631', '6707', 'K', 'Q', '2273', '1249', 'v', 'H', '1661', 'p', 'o', 'h', 'o', 'm']