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.
['5575', 'J', 'n', '5221', 'X', '3321', '7759', '3085', '4297', 'z', '6455', 'R', '9557', 'e', '2099', '9459', '5795']