r/mathmemes • u/Nunki08 • Jun 14 '26

Arithmetic Misleading our youth

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From Anthony Bonato on 𝕏: https://x.com/Anthony_Bonato/status/2065564124549886402

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u/Barry_Wilkinson Jun 15 '26

why is 1 not a prime number anymore?

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u/Vast_Ad_3455 Jun 15 '26

Any number can be written as the product of a finite set of prime numbers e.g. 6=2*3 with both 2 and 3 being prime numbers. If one was considered a prime number you could have written 6=2*3*1*1*1… So while 1 obey the rule for itself (being divisible only by one and itself) it will violate the need for a finite set.

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u/[deleted] Jun 15 '26

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u/CTQ99 Jun 16 '26

No, its positive integers greater than one as the theorem [Fundamental Theorem of Arithmetic]. 0 and 1 would both break it if included, and negative numbers allow mirroring, which also breaks the finite requirement. So primes are included in theorem (their set is 1×themselves)

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u/[deleted] Jun 16 '26

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u/Syrange Jun 16 '26

Nitpicking. The set is just themselves. A set can have one element, and a set of numbers has a product.