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', '9203', '9839', 'r', 'N', '6807', 'H', '719', '4751', 'q', 'i', 'a', '1253', 'B', '1025', 'i', '8773', '4929', '4967', '2245']