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.
['1061', 'J', '1621', 'O', '4291', 'J', '933', 'V', '6739', 'R', '1619', '4293', 'i', 'N', '89', '2749', '7111', '1463']