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.
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Question: ['Q', '2271', '1803', '2363']

Answer: 6437


Question: ['k', 'Z', 'r', 'K', 'b', 'X', 'A']

Answer: 0


Question: ['6651', '8595', '6039', '8377']

Answer:
29662