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', '3109', 'q', '6711', '4701', '9819', 'd', 's', '3347', 'm', 'u', 'c', '8233', 'W', 'N', 'j', '3501', 'q']