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.
['3923', '6463', '2849', 'v', '4377', '2659', 'F', '1201', '3327', 'd', 'P', '8733', 'm', 'D', '2021', 'g', 'O', 'V', 'L']