OT - Prime number puzzle

QuikSand · 08-08-2003, 08:23 AM

Primes are always a weird source of math conjecture - but this one doesn't involve any real higher-order thinking, I don't think.

Take a number like 54. It's not prime, of course, but if we changed one digit, we could make it into a prime. In this case, if we adjust the digit 4 into a 3, we get 53 - which is a prime. (We also could have adjusted the 4 into a 9 - it doesn't have to be an adjustment by any particular incremnt - just a change to any other single digit)

The puzzle is this: what is the smallest number that cannot be changed into a prime by modifying one of its digits?

Bonegavel · 08-08-2003, 08:24 AM

21

[edit: sorry, I thought this was another Quik gambling thread. My eyes glazed over after the first sentence of post and I made the rest up myself. I thought we were playing BlackJack.]

mrsimperless · 08-08-2003, 08:27 AM

Alan T · 08-08-2003, 08:28 AM

200 ?

mrsimperless · 08-08-2003, 08:30 AM

Figures I would find the SECOND lowest one...

Nice job Alan, I'm guessing that you found it.

Alan T · 08-08-2003, 08:34 AM

I guess it shows though that it took me 1 minute longer to count prime numbers than you

mrsimperless · 08-08-2003, 08:38 AM

Not really. I, um.... used a resource.

Prime numbers list

Bee · 08-08-2003, 08:44 AM

Alan T · 08-08-2003, 08:48 AM

Quote:

Originally posted by mrsimperless
Not really. I, um.... used a resource.

Prime numbers list

Doh

QuikSand · 08-08-2003, 09:43 AM

200 is correct, of course. Nicely done.

08-08-2003, 08:24 AM	#2
Bonegavel Awaiting Further Instructions... Join Date: Nov 2001 Location: Macungie, PA	21 [edit: sorry, I thought this was another Quik gambling thread. My eyes glazed over after the first sentence of post and I made the rest up myself. I thought we were playing BlackJack.] __________________ Last edited by Bonegavel : 08-08-2003 at 08:26 AM.

08-08-2003, 08:27 AM	#3
mrsimperless College Prospect Join Date: Apr 2003	202 __________________ "All I know is that smart women are hot. Susan Polgar beat me in 24 moves in a simultaneous exhbition. I slept with the scoresheet under my pillow." Off some dude's web site.

08-08-2003, 08:28 AM	#4
Alan T Hall Of Famer Join Date: Dec 2002 Location: Mass.	200 ? __________________ Couch to ??k - From the couch to a Marathon in roughly 18 months.

08-08-2003, 08:30 AM	#5
mrsimperless College Prospect Join Date: Apr 2003	Figures I would find the SECOND lowest one... Nice job Alan, I'm guessing that you found it. __________________ "All I know is that smart women are hot. Susan Polgar beat me in 24 moves in a simultaneous exhbition. I slept with the scoresheet under my pillow." Off some dude's web site.

08-08-2003, 08:34 AM	#6
Alan T Hall Of Famer Join Date: Dec 2002 Location: Mass.	I guess it shows though that it took me 1 minute longer to count prime numbers than you __________________ Couch to ??k - From the couch to a Marathon in roughly 18 months.

08-08-2003, 08:38 AM	#7
mrsimperless College Prospect Join Date: Apr 2003	Not really. I, um.... used a resource. Prime numbers list __________________ "All I know is that smart women are hot. Susan Polgar beat me in 24 moves in a simultaneous exhbition. I slept with the scoresheet under my pillow." Off some dude's web site. Last edited by mrsimperless : 08-08-2003 at 08:39 AM.

08-08-2003, 08:44 AM	#8
Bee Pro Starter Join Date: Oct 2000 Location: Fairfax, VA	2/3

08-08-2003, 09:43 AM	#10
QuikSand lolzcat Join Date: Oct 2000 Location: Annapolis, Md	200 is correct, of course. Nicely done.

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