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.
['P', '4461', 'J', '6115', '1335', 'u', '499', '3327', '225', '49', '7919', 'Q', 'F', 'g', '1483', '6855', '6213', 'T', '2269']