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MathNet 2015-part-04 — 191 problems (EN–VI) Question 126

Math Olympiad Vault · MathNet 2015-part-04 — 191 problems (EN–VI)

Question 126

Find all positive integers $N$ having an even number of digits (no leading zeroes) such that, if we insert a multiplication sign after the first $n$ digits of $N$, the result of the multiplication is a divisor of $N$.