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.
['1969', 'R', '5989', 'd', '8507', '5925', 'T', 'D', 'd', 'H', 'F', 'q', '8365', 'D', 'N', 'k', '5061', '4859']