Prove that there exists a positive non-prime integer such that if any three of its neighboring digits are replaced with any given triple of the digits, the number remains non-prime. Does there exist a $1997$-digit such number?
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Tags: Grade 8, 1997
Prove that there exists a positive non-prime integer such that if any three of its neighboring digits are replaced with any given triple of the digits, the number remains non-prime. Does there exist a $1997$-digit such number?