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.
['4159', '7533', '6757', '69', '3787', '6771', 'V', '4317', '8769', '5843', '9231', 'S', 'q', '9299', 'V', 'I', '3673', '9595', '1969']