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.
['E', '9277', 'p', '45', '9343', '203', '4979', 'w', '7949', '9803', 'Y', '2693', 'I', '8343', '495', 'W', '6749', 'M']