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.
['4919', 'y', '2399', '8153', '6451', 'A', '7231', 'd', 'D', 'j', 'q', '7703', '5487', '2829', '1237', 'I', 'l', '2743', 'G', '1445']