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.
['q', '7401', 'm', '9541', '1431', '6155', '5525', '2187', '3935', '3579', '8227', 't', 'x', 'n', 'm', 'j', 'k', '7339', '3693', 'j']