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.

['7755', '8383', 'y', 'k', '4869', '2809']
23816

['b', 'W', 'V', 'R', '3761', 'U', '4553', '1803', 'W', '7775', '1067', 'Y', 'D', '3159']
22118

['i', '6215', '4897', 'P', '8263', 'N', '1573']

20948