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IMAS 2013–2014 Junior Division — Round 2 Question 15

IMAS · IMAS 2013–2014 Junior Division — Round 2

Question 15

A positive integer $x$ with $n\ge2$ digits is written down twice in a row and the $2n$-digit number so obtained is divisible by $x^2$. Prove that the first two digits of $x$ are 1 and 4 in that order.