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.
['419', '8781', '3671', '9129', '3121', '7815', '3341', '3923', '3225', '1187', '5065', 'i', '6191', 'q', 'z', '9911', '8307', '4627', '5323', 'u']