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.

['6921', 'a', 'U', '2821', '2111', 'h', '3937', '3697', 'd', '6309', 'q', '7961', '5287', '5375', '2721', '4523', 'V', '8633', 'c', '7643']
67939

['P', '6299', '9655', 'l', '6317', '2139', '3347', 'l', '3095', '7363', '3115', '7529', 'R']
48859

['8615', '4067', 'p', '5913', '991', 'Y', 'M']

19586