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.
['Q', 'h', '4987', 'g', 's', 'r', '5441', 'a', '6341', '9627', '3971', 'p', 'N', 'a', 'w', 'B', '5817', '8865', '107', '7727']