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: ['N', 'O', '2635', '8891']

Answer: 11526


Question: ['57', '9977', '2657', 'p', '9573', '7745', '4755', 'U']

Answer: 34764


Question: ['7239', 'y', 'I', 'B', 'z']

Answer:
7239