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.
['u', 'p', '2605', 'C', 'D', 'G', 'U', '1667', '8007', 'x', '2245', '4909', 'z', 'd', 'a', 'W', '8967', '5125', '3753']