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.
['m', 'p', '3761', 'X', '7141', '5407', '7447', '8407', '1123', 'Q', '1101', 'q', 'Y', '1467', '4075', '9887', '5289', '1425']