xkcd #3137: Cursed Number

Title text:

Another group of mathematicians is working to put an upper bound on the number, although everyone keeps begging them to stop.

Transcript:

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Source: https://xkcd.com/3137/

explainxkcd for #3137

461 points · 28 comments · view on lemmy.world

28 Comments

badcommandorfilename@lemmy.world · 40 pts · 343d

print(uuid())

palordrolap@fedia.io · 31 pts · 343d (6 replies)

Felt like noodling a little with some numbers. I have a nice candidate. 22301. Pretty small, right? ~~It's prime.~~ That's not troubling to most anyone's sanity. Edit: one should check one's silly code more carefully before madly pretending to be mad on the Internet. It is not prime. But the intermediate numbers still are.

There's something that can be done to that number four times (but no more) which results in a prime each time and the fourth step results in a 70 digit number that I may have looked at slightly tOo LoNnNg.

Edit 2: Attempt at redemption for the math if not the joke: Start with 5497949 which is prime, and you can do the thing four times and get a prime each time. The last one has 108 digits and, no word of a lie, starts 6969...

Imaginary bonus points for guessing what the heck the operation / something is.b

Audalin@lemmy.world · 23 pts · 343d (3 replies)

But 22301 isn't prime? It's 29*769.

palordrolap@fedia.io · 34 pts · 343d (2 replies)

Well, this is embarrassing. This is what I get for mathing after midnight.

porl@lemmy.world · 9 pts · 343d (1 reply)

The true number messed you up so much you can't recall it any more.

scathliath@lemmy.dbzer0.com · 2 pts · 342d

Can confirm, it stole my lunch money when I tried to see it, then gaslit me and told me my fiancee did. Truly a cursed number.

jaupsinluggies@feddit.uk · 8 pts · 342d (1 reply)

If you divide it by itself and add one, you can do that infinitely many times and get a prime every time. Works for all the primes.

sga@piefed.social · 1 pts · 341d

it also works for all perfect numbers (by definition non prime), and also triangle numbers (all triangle numbers greater than 3 or non prime), and also for all numbers above 42, and below 69. quite a neat property sir.

four@lemmy.zip · 27 pts · 343d (1 reply)

A moment of silence for all those who sacrificed themselves in the name of science

ZoteTheMighty@lemmy.zip · 10 pts · 343d

Actually, this isn't useful, so we still let it be called "math".

IndustryStandard@lemmy.world · 14 pts · 342d (4 replies)

The cursed number is pi. Everyone who tries to fully read it dies. This is why we shortened it to 3.14.

UnrepententProcrastinator@lemmy.ca · 5 pts · 342d (2 replies)

You can just use 3.

whoisearth@lemmy.ca · 4 pts · 342d

Meh close enoigh

Cocodapuf@lemmy.world · 2 pts · 342d

I like 22/7

sga@piefed.social · 4 pts · 341d

everyone who has ever heard of pi, has either died, or will die. just thought of pi gives you a chronic illness which can not be cured

Big_Boss_77@lemmynsfw.com · 9 pts · 343d

SCP-2.6*10^21^

DarkCloud@lemmy.world · 9 pts · 343d

Sounds like those stupid Rationalist cult groups who spend their time coming up with AI fantasies, and claim some thought-experiments are so powerful they'll ruin your mind - real immature stuff. Deserves to be lampooned like this.

nialv7@lemmy.world · 6 pts · 342d (1 reply)

If a number is long enough human won't be able to perceive it all at once, so in fact there are only finite number of cases we need to check.

Jankatarch@lemmy.world · 3 pts · 342d

Human will run out of memory when reading the number, in fact.

ripcord@lemmy.world · 6 pts · 343d (1 reply)

Sounds like the seed of an SCP.

Swedneck@discuss.tchncs.de · 1 pts · 339d

peep the horror

Dasus@lemmy.world · 4 pts · 342d

Sure there's quite a lot of them to choose from, but for instance USPS tracking numbers are 22-digit numbers.

tisktisk@piefed.social · 4 pts · 343d (3 replies)

I'm confused, what is this new lower bound specifically?