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    It always upsets me that 1 isn’t prime.

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      It’s just a convention. It would make a bunch of theorems annoying to state if 1 were prime.

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        “1 is a prime” can be the new “tau is superior to pi”.

        On a more serious note, I read a bit about this and apparently for a long time 1 wasn’t even considered a number: https://blogs.scientificamerican.com/roots-of-unity/why-isnt-1-a-prime-number/

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          The current ad-hoc definition of a prime is of a natural number with exactly two distinct positive natural divisors. It appeared to be convenient so it was normalized this way about one century ago (but you can still find very old books citing 1 as the first prime number).

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            2 being prime is pretty disappointing as well.

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              1 is only divisible by 1 and itself, but then considering it as prime will destroy “sieve of eratosthenes”

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              I ran out of time after 30 numbers.

              Does it tell you if you get something wrong?

              Update: ah, yeah, you lose immediately.

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                1 to 100 shouldn’t be hard, you could also make games like “Is this perfect square?”, “Is this perfect Cube?”