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MathNet 2006 — Part 04 Question 199

Math Olympiad Vault · MathNet 2006 — Part 04

Question 199

A positive integer $n$ is called "flippant" if $n$ does not end in $0$ (when written in decimal notation) and, moreover, $n$ and the number obtained by reversing the digits of $n$ are both divisible by $7$. How many flippant integers are there between $10$ and $1000$?