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.
['I', 'm', '6745', 'z', '2777', 'j', '9619', '7789', 'X', 'F', 'o', '1177', 'w', '9627', '891', 'Z', 'n', 'J', '9093', '6829']