RailUK Forums
RailUK Forums > Other Forums > Quizzes & Games


Reply
 
Thread Tools
Old 13th December 2016, 21:17   #8416
DaleCooper
Established Member
 
DaleCooper's Avatar
 
Join Date: 2 Mar 2015
Location: No.664 - Next door to the Beast
Posts: 2,063
Default

They are a type of Mersenne prime?
DaleCooper is offline   Reply With Quote
Registered users do not see these banners - join today!
Old 14th December 2016, 21:17   #8417
me123
Established Member
 
me123's Avatar
 
Join Date: 9 Jul 2007
Location: Clwyd
Posts: 8,084
Default

You are very close, but they are not all Mersenne primes. Have a think about what Mersenne primes are and you should get there.
--- old post above --- --- new post below ---
Bump.

I'm really surprised no-one's got this yet. Because Dale's last guess was sooooo close!

Just to recap:
1) We know that they're all prime numbers, but the link is more complex than just that.
2) Not all of the numbers are in themselves Mersenne primes (that's a bit of a hint!), but Mersenne primes are an important part of the answer.

As another hint: the sequence is conjectured to have infinite members, yet only 49 have been identified thus far. The largest known number in the sequence is 74,207,281.

Last edited by me123; 14th December 2016 at 21:18. Reason: Double post prevention system
me123 is offline   Reply With Quote
Old 14th December 2016, 21:40   #8418
DaleCooper
Established Member
 
DaleCooper's Avatar
 
Join Date: 2 Mar 2015
Location: No.664 - Next door to the Beast
Posts: 2,063
Default

I don't understand it really but it appears to be something to do with Mersenne prime exponents which when applied to an equation I can't type here results in Mersenne primes - does that make any sense?

As for being surprised; I don't think you should be.
DaleCooper is offline   Reply With Quote
Old 14th December 2016, 22:12   #8419
me123
Established Member
 
me123's Avatar
 
Join Date: 9 Jul 2007
Location: Clwyd
Posts: 8,084
Default

^You've essentially got it.

It was a deliberately difficult question, but I was quite surprised that you got so close and then stopped guessing when you were almost there! I thought someone was going to get it last night.

For those who don't know:
A prime number is a whole number divisible only by itself and 1. For example, 3 is a prime number (divides by 3 and 1 only), whereas 4 is not (divides by 4 and 1, but also 2).
A Mersenne prime is a subset of prime numbers that can be expressed in the following format:
M(P)=(2^P)-1 - i.e. the prime number is one less than a power of two.

All the exponents that create a Mersenne prime are themselves prime numbers, but the exponent being prime does not guarantee

And that's what these numbers are. These are the primes that, when substituted for the value of P in the above equation, give you Mersenne primes. These are the prime exponents that generate Mersenne primes.

2 is not a Mersenne prime (hence why I couldn't accept your last answer), but 2^2 = 4, 4-1 is 3. 3 is a Mersenne prime. The numbers get big really quickly - the largest known Mersenne prime (2^74,207,281-1) has over 22 million digits.

Anyway, Dale's floor.
me123 is offline   Reply With Quote
Old 14th December 2016, 23:20   #8420
Cowley
I'm only here to relax
Established Member
 
Cowley's Avatar
 
Join Date: 14 Apr 2016
Location: Devon
Posts: 1,553
Default

Quote:
Originally Posted by me123 View Post
^You've essentially got it.

It was a deliberately difficult question, but I was quite surprised that you got so close and then stopped guessing when you were almost there! I thought someone was going to get it last night.

For those who don't know:
A prime number is a whole number divisible only by itself and 1. For example, 3 is a prime number (divides by 3 and 1 only), whereas 4 is not (divides by 4 and 1, but also 2).
A Mersenne prime is a subset of prime numbers that can be expressed in the following format:
M(P)=(2^P)-1 - i.e. the prime number is one less than a power of two.

All the exponents that create a Mersenne prime are themselves prime numbers, but the exponent being prime does not guarantee

And that's what these numbers are. These are the primes that, when substituted for the value of P in the above equation, give you Mersenne primes. These are the prime exponents that generate Mersenne primes.

2 is not a Mersenne prime (hence why I couldn't accept your last answer), but 2^2 = 4, 4-1 is 3. 3 is a Mersenne prime. The numbers get big really quickly - the largest known Mersenne prime (2^74,207,281-1) has over 22 million digits.

Anyway, Dale's floor.
I never was very good at maths.
Cowley is offline   Reply With Quote
Old 15th December 2016, 00:17   #8421
theageofthetra
Established Member
 
Join Date: 27 May 2012
Posts: 1,798
Default

How is any of this 'general knowledge'?
theageofthetra is offline   Reply With Quote
Old 15th December 2016, 06:09   #8422
krus_aragon
Established Member
 
krus_aragon's Avatar
 
Join Date: 10 Jun 2009
Location: North Wales
Posts: 2,200
Default

Quote:
Originally Posted by theageofthetra View Post
How is any of this 'general knowledge'?
In general, by reading this thread, you gain knowledge.

More realistically, this thread does swing back and forth through different topics. We've had stints of all sorts of questions over the many pages of the thread. If you want to steer the quiz, grab an open floor and set a question!
krus_aragon is offline   Reply With Quote
Old 15th December 2016, 07:23   #8423
me123
Established Member
 
me123's Avatar
 
Join Date: 9 Jul 2007
Location: Clwyd
Posts: 8,084
Default

Quote:
Originally Posted by theageofthetra View Post
How is any of this 'general knowledge'?
Very much applied general knowledge. Knowing that there are pretty smart people on here, it seemed perfectly reasonable to post a challenging question and they lived up to it. Within two guesses we were within a whisker of the real answer. I'd argue that it was a much better question than three random numbers that happen to relate to airline ordering codes. It's amazing how many questions quickly descend into "guess what I'm thinking" (Odd One Out rounds being particularly prone to this). I had a difficult, but clear question with (I think) just one possible answer (although I would have accepted any other answers that coincidentally happened to work).

But I'll keep quiet from now on then.

Last edited by me123; 15th December 2016 at 07:30.
me123 is offline   Reply With Quote
Old 15th December 2016, 09:32   #8424
AlterEgo
Around and About
Established Member
 
Join Date: 30 Dec 2008
Location: Surrey
Posts: 6,627
Default

Quote:
Originally Posted by theageofthetra View Post
How is any of this 'general knowledge'?
It is difficult to have a proper trivia quiz on a forum in the age of Google and Wikipedia.
__________________
My YouTube Channel
AlterEgo is offline   Reply With Quote
Old 15th December 2016, 09:33   #8425
DaleCooper
Established Member
 
DaleCooper's Avatar
 
Join Date: 2 Mar 2015
Location: No.664 - Next door to the Beast
Posts: 2,063
Default

Quote:
Originally Posted by theageofthetra View Post
How is any of this 'general knowledge'?
I'm no mathematician but I had heard the term "Mersenne prime" so I took gamble with my first guess. me123's response and the lack of any other guesses led me to do a bit of research which anyone could have done.

Quote:
Originally Posted by krus_aragon View Post
In general, by reading this thread, you gain knowledge.

More realistically, this thread does swing back and forth through different topics. We've had stints of all sorts of questions over the many pages of the thread. If you want to steer the quiz, grab an open floor and set a question!
I agree with this; those questions I can't answer are more valuable because I learn something.

Quote:
Originally Posted by me123 View Post
Very much applied general knowledge. Knowing that there are pretty smart people on here, it seemed perfectly reasonable to post a challenging question and they lived up to it. Within two guesses we were within a whisker of the real answer. I'd argue that it was a much better question than three random numbers that happen to relate to airline ordering codes. It's amazing how many questions quickly descend into "guess what I'm thinking" (Odd One Out rounds being particularly prone to this). I had a difficult, but clear question with (I think) just one possible answer (although I would have accepted any other answers that coincidentally happened to work).

But I'll keep quiet from now on then.
Don't keep quiet, keep them coming. We need variety and despite the difficulty of your question it was 2^74,207,281-1 times better than an "Odd One Out" question.

Next question (which hopefully occupies the middle ground):

Where do electric fans come with a health warning?
DaleCooper is offline   Reply With Quote
Old 15th December 2016, 10:10   #8426
ComUtoR
Established Member
 
Join Date: 13 Dec 2013
Location: UK
Posts: 2,950
Default

Quote:
Originally Posted by DaleCooper View Post
Where do electric fans come with a health warning?
'Cause people are idiots.

They come with cages because people put fingers in them and they often have flappy things attached because people need to see when they are on.

Is this anything to do with having a Kite mark or requiring labelling standards.

Or simply.... the EU made us do it

Or tinking about it. Is it because the spread of infections diseases etc can be increased by the flow of air around a room ?
__________________
The Death Knell of the Guards sounded
and lo, the forums rejoiced.
ComUtoR is offline   Reply With Quote
Old 15th December 2016, 10:14   #8427
AlterEgo
Around and About
Established Member
 
Join Date: 30 Dec 2008
Location: Surrey
Posts: 6,627
Default

Quote:
Originally Posted by ComUtoR View Post
'Cause people are idiots.

They come with cages because people put fingers in them and they often have flappy things attached because people need to see when they are on.

Is this anything to do with having a Kite mark or requiring labelling standards.

Or simply.... the EU made us do it

Or tinking about it. Is it because the spread of infections diseases etc can be increased by the flow of air around a room ?
The question was where, not why.

I am sure the answer to this is South Korea, which has a famous fan death hysteria.
__________________
My YouTube Channel
AlterEgo is offline   Reply With Quote
Old 15th December 2016, 10:45   #8428
DaleCooper
Established Member
 
DaleCooper's Avatar
 
Join Date: 2 Mar 2015
Location: No.664 - Next door to the Beast
Posts: 2,063
Default

Quote:
Originally Posted by AlterEgo View Post
I am sure the answer to this is South Korea, which has a famous fan death hysteria.
South Korea is the correct answer and it's more than hysteria, government agencies have actually advised against using electric fans when sleeping in rooms with the windows closed.

https://en.wikipedia.org/wiki/Fan_death
https://skeptoid.com/episodes/4287
DaleCooper is offline   Reply With Quote
Old 15th December 2016, 14:53   #8429
AlterEgo
Around and About
Established Member
 
Join Date: 30 Dec 2008
Location: Surrey
Posts: 6,627
Default

I assume it's my floor.

What's unusual about a map of this place?

https://www.google.co.uk/maps/place/...51!4d-0.744019
__________________
My YouTube Channel
AlterEgo is offline   Reply With Quote
Old 15th December 2016, 15:24   #8430
TheEdge
Probably tripping a 90
Established Member
 
TheEdge's Avatar
 
Join Date: 29 Nov 2012
Location: Norwich
Posts: 2,415
Default

Well at first I thought it was the Microsoft XP field but then realised it wasn't in the US. Then I threw in a Google search for the locale in case it was the site of some ancient city.

And then the answer presented itself. That field is OS Square SE830220, the most desolate grid square in the UK with no features at all.
__________________
Well it was fine when I prepped it...
Opinions/views are my own and not of my employers
TheEdge is offline   Reply With Quote
Reply

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



All times are GMT. The time now is 00:48.
Powered by vBulletin® Version 3.8
© RailUK Forums 2005 - 2017