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.
['w', '9155', 'H', '7647', 's', '2747', 'W', 'X', 'X', 'g', '5953', '6855', '9077', 'S', 'T', 'l', '7355', '6511']