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Prime numbers so memorable that people hunt for them

scientificamerican.com

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Re: Prime numbers so memorable that people hunt for them

#81

Post by Uptrenda »

isaacfrond wrote: post #78

Since prime numbers are very useful in secure communication, such easy-to-remember large prime numbers can be of great advantage in cryptography, That's nonsense. I'm sure there thinking of RSA, but that needs secret prime numbers. So easy-to-remember is pretty much the opposite of one want. Also they are way to big. 2048 bit RSA needs two 300 digit prime numbers.

Yeah, I'm no expert on mathematical cryptography but I was thinking the same. Now what would be cool is... finding memorable public keys. That would solve the key exchange problem and allow for secure names without a register. But the closest I've seen is brute forced ECDSA key pairs that hash to having a vanity starting prefix.

I suppose some inspiration from brain wallets and encoding schemes could be used to transform any public key into something more memorable.

Re: Prime numbers so memorable that people hunt for them

#82

Post by tkgally »

tkgally wrote: post #62

My family’s phone number when I was a child was both a palindrome and a prime: 7984897. My parents had had the number for two decades without noticing it was a palindrome. I still remember my father’s delight when he got off a phone call with a friend: “Doug just said, ‘Hey, I dialed your number backwards and it was still you who answered.’ I never noticed that before!” A few years later, around 1973, one of the othe…

Follow-up: My formal study of programming stopped with that Fortran IV class a half century ago, but LLMs now delude me into thinking I can program. I just had Claude write me a Python program to list all of the seven-digit numbers that are both primes and palindromes. It found 668: 1003001, 1008001, 1022201, 1028201, 1035301, ...

Re: Prime numbers so memorable that people hunt for them

#84

Post by pwg »

nlh wrote: post #72
stevelosh wrote: post #36

If you were around in the 80's and 90's you might have already memorized the prime 8675309 ( https://en.wikipedia.org/wiki/867-5309/Jenny ). It's also a twin prime, so you can add 2 to get another prime (8675311).

My other favorite fun fact about this number (other than this new prime info which I am excited to have learned) is that in almost every store I’ve tried it, someone has used that (along with a local area code) as the phone number for a store loyalty card. I’m a Bay Area guy, so if you’re ever at Safeway and need to get the discount without giving up your personal info, 415-867-5309 has got ya covered ;)

> someone has used that (along with a local area code) as the phone number for a store loyalty card.

Usually because for far too long, noisy retailers wanted a "phone number" upon checkout (even if one was paying cash -- Radio Shack was an especially bad one back in the day). For those who didn't want to get yet more telemarketing calls, repeating "Jenny's number" [1] from the song was a way to "just buy" whatever it was you wanted. The minimum wage cashier didn't care, but the cash register demanded "a number". So giving the cashier Jenny's number worked.

This has largely faded now that they can track everyone via one's credit card numbers.

[1] https://en.wikipedia.org/wiki/867-5309/Jenny

Re: Prime numbers so memorable that people hunt for them

#85

Post by pwg »

hatthew wrote: post #57

> Since prime numbers are very useful in secure communication, such easy-to-remember large prime numbers can be of great advantage in cryptography What's the use of notable prime numbers in cryptography? My understanding is that a lot of cryptography relies on secret prime numbers, so choosing a notable/memorable prime number is like choosing 1234 as your PIN. Are there places that need a prime that's arbitrary, larg…

RSA [1] is directly based on the difficulty of factoring very large numbers where the factors of the number are also prime numbers.

[1] https://en.wikipedia.org/wiki/RSA_(cryptosystem)

Re: Prime numbers so memorable that people hunt for them

#86

Post by noahjk »

pwg wrote: post #84
nlh wrote: post #72

Earlier quoted context omitted.

My other favorite fun fact about this number (other than this new prime info which I am excited to have learned) is that in almost every store I’ve tried it, someone has used that (along with a local area code) as the phone number for a store loyalty card. I’m a Bay Area guy, so if you’re ever at Safeway and need to get the discount without giving up your personal info, 415-867-5309 has got ya covered ;)

> someone has used that (along with a local area code) as the phone number for a store loyalty card. Usually because for far too long, noisy retailers wanted a "phone number" upon checkout (even if one was paying cash -- Radio Shack was an especially bad one back in the day). For those who didn't want to get yet more telemarketing calls, repeating "Jenny's number" [1] from the song was a way to "just buy" whatever it…

Does contactless payment help at all? I know it uses a different card number, but I’m not sure if it’s a rotating number.

Re: Prime numbers so memorable that people hunt for them

#87

Post by pwg »

noahjk wrote: post #86
pwg wrote: post #84

Earlier quoted context omitted.

> someone has used that (along with a local area code) as the phone number for a store loyalty card. Usually because for far too long, noisy retailers wanted a "phone number" upon checkout (even if one was paying cash -- Radio Shack was an especially bad one back in the day). For those who didn't want to get yet more telemarketing calls, repeating "Jenny's number" [1] from the song was a way to "just buy" whatever it…

Does contactless payment help at all? I know it uses a different card number, but I’m not sure if it’s a rotating number.

If a given retailer gets the same number off your card each time you do contactless, then that retailer /could/ track you via that number.

If all retailers get the same number, then they can each track you, and correlate your purchases between themselves.

Note, there just needs to be /some/ constant number from whatever comes through via contactless, the number does not have to be the magic numbers that post the sale to the card.

Re: Prime numbers so memorable that people hunt for them

#88

Post by Dylan16807 »

noahjk wrote: post #86
pwg wrote: post #84

Earlier quoted context omitted.

> someone has used that (along with a local area code) as the phone number for a store loyalty card. Usually because for far too long, noisy retailers wanted a "phone number" upon checkout (even if one was paying cash -- Radio Shack was an especially bad one back in the day). For those who didn't want to get yet more telemarketing calls, repeating "Jenny's number" [1] from the song was a way to "just buy" whatever it…

Does contactless payment help at all? I know it uses a different card number, but I’m not sure if it’s a rotating number.

It doesn't rotate. Also it looks like if you use the contactless method built into the actual card it doesn't use a different number.

Re: Prime numbers so memorable that people hunt for them

#89

Post by bongodongobob »

dchichkov wrote: post #63
bongodongobob wrote: post #53

Earlier quoted context omitted.

Can we stop with the "haha llms can't do math" nonsense? You'll one shot it every time if you tell it to use Python. You're holding it wrong.

Sorry, but this was ChatGPT/o1 with access to code execution (Python) and it used almost 4 minutes to do reasoning. It had done a few checks with smaller numbers, all of which had failed. And it proceeded to make a wrong conclusion (with high confidence).

Of course it failed. Tell it to write a program.

Re: Prime numbers so memorable that people hunt for them

#90

Post by noman-land »

dhosek wrote: post #71
tkgally wrote: post #62

My family’s phone number when I was a child was both a palindrome and a prime: 7984897. My parents had had the number for two decades without noticing it was a palindrome. I still remember my father’s delight when he got off a phone call with a friend: “Doug just said, ‘Hey, I dialed your number backwards and it was still you who answered.’ I never noticed that before!” A few years later, around 1973, one of the othe…

I thought everybody factors phone numbers. I also factor the odometer reading in my car while driving.

How do you do mental factoring?
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