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.
['x', 'P', 'z', '2341', 'o', '7719', 'q', 'p', 'k', 'x', 'T', 'g', '3325', 'R', '6603', '8483', '8093', 'r']