Question 75
Let $a$, $b$ and $c$ be non-zero digits. Let $p$ be a prime number which divides the three-digit numbers $abc$ and $cba$. Show that $p$ divides at least one of the numbers $a+b+c$, $a-b+c$ and $a-c$.
Math Olympiad Vault · MathNet 2010 — Part 06