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', 'x', 'L', 'I', 'P', '669', '8051', 'n', '7285', '6605', 'V', '3459', 's', '1987', 'B', '5211', 'a', 'o', 'Y', '9063']