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threelonmusketeers@sh.itjust.works to Math Memes@lemmy.blahaj.zoneEnglish · 8 months ago

John Conway proves that 91 is the smallest number which looks prime but isn't

www.youtube.com

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John Conway proves that 91 is the smallest number which looks prime but isn't

www.youtube.com

threelonmusketeers@sh.itjust.works to Math Memes@lemmy.blahaj.zoneEnglish · 8 months ago
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  • erie09@lemmy.world
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    8 months ago

    I always felt that 21 should be, but nooo. Stupid 7

    • threelonmusketeers@sh.itjust.worksOP
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      8 months ago

      21 should be

      2 + 1 = 3, therefore 21 is divisible by 3 and is not prime. QED :)

      • BigDanishGuy@sh.itjust.works
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        8 months ago

        9+1 = 10, therefore 91 is divisible by 10 and is not a prime … QED, I guess

        • humorlessrepost@lemmy.world
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          8 months ago

          In the right base, that might work.

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