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.
['4639', '3427', '8985', 'I', '919', '3325', '2803', '7519', 'y', '4803', 'm', 'F', '2551', '9189', 'p', 'P', '3611', '2433']