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.
['Y', '4669', 'x', 'V', '5137', '6193', 'w', '2371', '6691', '5561', '8767', '1223', 'r', 'E', 'b', '5089', '5687', 'M', 'o', 'X']