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MathNet 2018-part-02 — 181 problems (EN–VI) Question 84

Math Olympiad Vault · MathNet 2018-part-02 — 181 problems (EN–VI)

Question 84

A positive integer is called *Babylonic* if it is greater than $9$, and if its base-$60$ representation is the same as its decimal representation without the first digit. For example, the number $123$ is Babylonic since $123 = (23)_{60}$. How many Babylonic numbers less than $10\,000$ are there? (Mea Bombardelli)