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.
['R', 'X', 'l', '3881', '6037', 'Q', 'v', 'Q', '5795', 'd', 'Y', '1847', '4867', 'S', 'z', 'C', '4203', 'C']