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.
['Z', 'l', 'f', 'Y', '5987', '5291', 'X', 'A', 'd', '9287', '5847', '3413', 'I', 'M', 'A', 'u', '7849', '4941']