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.
['z', 'T', 'Y', 's', 'j', '585', '7833', '2601', '8057', 'S', '7037', '5799', '4477', '5377', '6301', 'P', 'm', '9431', 'f']