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: ['2087', '8171', 'c', 'd', 'a', '5621', 'n']

Answer: 15879


Question: ['E', 'X', 'C', 'v', '2803', 'g', 'b', '763']

Answer: 3566


Question: ['4397', 'U', '8515', 't']

Answer:
12912