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.

['t', '7469', 'Y', 'N', '8137']
15606

['R', 'I', 'f', 'K', 'p', '8579', 'e', '1223', 'I', 'K', '8311', '2147', '4241', 'z', '6671', 'r']
31172

['4981', '1851']

6832