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.
['N', 'O', '2467', '9881', '7883', '167', 'E', '4001', 'V', 'T', 'A', '3657', '199', '9203', '1763', 'P', '7953', 'R', 'U']