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.
['Z', '9941', '8847', '5041', 'Y', 'v', '611', '1871', 'T', 'b', 'U', 'n', 'd', '7777', '9745', 'v', '8063', '8407', 'S', '4051']