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.

['3145', 'C', '7725', 'k', 'z']
10870

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

['m', '9969', 'E']

9969