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.
['1215', '4275', 'l', 'E', '7167', 's', '5529', '8415', 'S', 'H', 'l', 'O', 't', 'X', 'm', 'v', '1297', 'V']