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.
['X', '4163', 'r', '5367', '3979', '2255', '7199', '5849', 'N', '5709', '9197', '1353', '1497', '6123', '137', 'y', 'u', 'B', '9267']