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.
['1189', '9841', 'H', 'K', '9801', '879', 'O', 'D', 'd', 'z', '7923', 'U', 'e', '6761', '339', '4185', '2877', 'j', '9345', 'q']