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.
['a', '5225', 'K', '6685', '5219', 'T', 't', 'm', 'G', '6583', '8753', 'N', '3205', 'p', '9293', '851', 'v', '5419', 'D', 'f']