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.
['7847', 'I', 'Z', '4811', '623', '6397', '8271', '4187', 'R', '9597', 'H', 'u', 'e', '527', '3761', 'b', '4509', 'm']