Tag Archives: Fermat

Four formats for Fermat

In my previous post I mentioned Fermat’s Little Theorem, a beautiful, fundamental result in number theory that underlies lots of things like public-key cryptography and primality testing. (It’s called “little” to distinguish it from his (in)famous Last Theorem.) There are … Continue reading

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New baby, and primality testing

I have neglected writing on this blog for a while, and here is why: Yes, there is a new small human in my house! So I won’t be writing here regularly for the near future, but do hope to still … Continue reading

Posted in meta, number theory, primes | Tagged , , , | 9 Comments

Book review: Fermat’s Enigma

Fermat’s Enigma: The Epic Quest to Solve the World’s Greatest Mathematical ProblemSimon Singh After having it recommended to me several times, I finally picked up this book when I happened to see it at our favorite local used bookstore. I … Continue reading

Posted in books, open problems, proof, review | Tagged , , , | 10 Comments

Fun with repunit divisors: proofs

As promised, here are some solutions to the repunit puzzle posed in my previous post. (Stop reading now if you don’t want to see solutions yet!) Prove that every prime other than 2 or 5 is a divisor of some … Continue reading

Posted in iteration, modular arithmetic, number theory, pattern, primes, proof | Tagged , , , , | 1 Comment