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.
['6055', '3105', 'z', 'g', '9189', '7839', 'N', 'o', '2395', '7469', 'x', '2325', '9767', '8157', 'Z', 't', '6599', '5829']