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.
['8801', 'W', '3909', 'b', '5911', '867', 'j', '1803', 'X', '1889', '6909', '6595', 'w', '1083', 'D', '8025', '3455', 'S', '2767']