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.
['y', 'm', '5541', '747', '4265', '9603', 'q', '9721', '9881', 'L', '6427', '8441', '6301', '617', 'K', 'U', 'Y', '319', '9035']