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.

['G', '7473', 'z', 'i', 'V', 'g', '621', 'K', '4473', 'd', '2711', '6609', 'q']

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
21887