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', '9943', 'D', '5005', 'G', '6031', 'u', '3287', 'k', 'E', '1091', '387', 'h', 'J', '4677', '9847', 'P', 'I']