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.
['3963', 'Q', 'U', 'd', 'l', 'I', 'T', 'J', '7657', 'Y', 'v', 'b', '5355', '9143', 'I', 's', '1887', 'y', '8091', '6081']