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Math Memes @lemmy.blahaj.zone threelonmusketeers @sh.itjust.works 2mo ago

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

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I always felt that 21 should be, but nooo. Stupid 7
- 21 should be
  
  2 + 1 = 3, therefore 21 is divisible by 3 and is not prime. QED :)
  
  9+1 = 10, therefore 91 is divisible by 10 and is not a prime ... QED, I guess
  
  In the right base, that might work.

19 comments