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.
['745', 'd', '8935', '603', 'M', '9221', 'N', 'f', 'W', '3083', '9285', '9565', 'I', 'C', '1277', '763', '8779', '5861', 'f']