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.
['4089', 'D', '6075', '9519', '3805', '3217', '8725', '3461', 'A', 'S', '2207', 'g', '7329', 's', '4011', '4441', 'a', 'T']