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.
['8625', '9289', '4361', '3953', '7945', '705', 'L', '4071', 'O', '817', '6407', 'D', 'x', 'v', '419', 'x', 'Z', 't', 'A']