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.
['4275', 'B', '4539', 'v', '7017', 'q', 'i', 'R', '5479', 'q', 'v', 'A', 'I', '5223', '6329', 'i', 'x', 'k']