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Date Dice

Posted: Tue Sep 08, 2009 8:46 pm
by Kieran Child
I have two dice that can be used to display any day of the month in numerical format. Today, they are showing 0 and 8.
Both dice are 6 sided. What are the numbers on each of the dice?
Please don't post the answer, because it's quite a nice puzzle I think. PM me the answer if you me to reward you as an obedient slave for a day.

Re: Date Dice

Posted: Tue Sep 08, 2009 8:58 pm
by Michael Wallace
Is this puzzle of your own construction?

Re: Date Dice

Posted: Tue Sep 08, 2009 9:00 pm
by Kieran Child
I honestly don't remember. It's jotted down in one of my older notebooks, but I haven't put a source by it.

Re: Date Dice

Posted: Tue Sep 08, 2009 9:05 pm
by Innis Carson
I have a calendar on my computer desk in front of me that consists of exactly what you described, so I found this puzzle quite easy.

Re: Date Dice

Posted: Tue Sep 08, 2009 11:05 pm
by Adam Dexter
I worked it out (I think) :)

Re: Date Dice

Posted: Wed Sep 09, 2009 12:18 am
by David Roe
Do I get bonus points if I tell you what the days and months are in Danish? Because that's where my date dice calender came from. And no, I'm not going to pm the answer. ;)

Re: Date Dice

Posted: Wed Sep 09, 2009 7:54 am
by Matt Bayfield
After first thinking this was impossible, I think I've worked it out.

Re: Date Dice

Posted: Wed Sep 09, 2009 8:47 am
by Kieran Child
Matt and Jon have solved it. They get to share the top prize of a high-end fridge.

Re: Date Dice

Posted: Wed Sep 09, 2009 9:03 am
by Jon Corby
Cool.

Re: Date Dice

Posted: Wed Sep 09, 2009 10:12 am
by Matt Morrison
Image

Re: Date Dice

Posted: Wed Sep 09, 2009 10:19 am
by Phil Reynolds
Kieran Child wrote:Matt and Jon have solved it.
Hello? :shock:

Re: Date Dice

Posted: Wed Sep 09, 2009 11:10 am
by Matt Bayfield
The referee is already flagging offside for references to Jon and I sharing our Smeg...

Re: Date Dice

Posted: Wed Sep 09, 2009 11:38 am
by Kieran Child
Oh Phil solved it too, also some other people, but I think I've replied to all of them.

Re: Date Dice

Posted: Sat Sep 12, 2009 12:51 pm
by Michael Wallace
I think this had had long enough without any replies now. Kieran - want to give some clues or are you happy for someone to just post the answer (or, indeed, post it yourself)?

Re: Date Dice

Posted: Sat Sep 12, 2009 12:58 pm
by Kieran Child
Fair point, hillariously made.
The main thing to notice is that 6 can be flipped as a 9. Once you realise this, the rest of it is just logic to fit together.
Both dice have 0,1,2 on them, and then 3,4,5,6,7,8 are spread over the two dice.
My answer in the book is this:
0,1,2,3,4,5
0,1,2,6,7,8

Re: Date Dice

Posted: Sat Sep 12, 2009 1:02 pm
by Michael Wallace
I thought I'd post my 'strategy' (for want of a better word) for this, since I found it moderately interesting.

You start off knowing you have 12 'spaces' available, and a total of 10 numbers that need to be printed at least once. This means at most 2 duplicates. So first you know you've got to have a 1 on each die, for 11, and a 2 on each die, for 22. You also have to have a 0 on each die, because it's impossible to have 01 up to 09 with a 0 on only one die. But now you've got three duplicates, which means you can't have every number, and so at least two digits now have to be represented on the same face.

Admittedly if you just spot the 6/9 thing at the start you can avoid all that, although at least this way you prove you can't do it without that sort of trick. (although there may well be an even more succinct way of showing it)

Re: Date Dice

Posted: Sat Sep 12, 2009 11:08 pm
by Sue Sanders
Oh. I'd been working on this before I saw you've given an answer.

To my mind, you don't need a zero on both dice because when it's the 1st, 2nd, 3rd etc, of the month, there's no rule mentioned that says you have to display it as 01, 02, 03. So I'd just put the one relevent one out on the first 9 days of the month. So then, as long as 1,2, and 3 are on the opposite one to 0, you can do it, and it saves on dusting!

But I admit, your way is more 'tricksey'

N.B note my careful avoidance of the term dice, dices and die as I've just suffered a mind blank as to which is singular and which plural.

Re: Date Dice

Posted: Sat Sep 12, 2009 11:12 pm
by Kieran Child
I hope to get rid of the 'displaying 8 as 8' idea by saying today was 08

Re: Date Dice

Posted: Sun Sep 13, 2009 8:12 am
by Sue Sanders
Kieran Child wrote:I hope to get rid of the 'displaying 8 as 8' idea by saying today was 08
Yes, I saw that and assumed that to be a lure in the wrong direction that was all part of the evilness of the puzzle. You see, I was trying to think outside the box!!! On which subject can you PM me the answer to the 3 houses/3 services puzzle please - I'm really busy at the moment and really need to stop being distracted by it! Ta.

Re: Date Dice

Posted: Sun Sep 13, 2009 9:45 pm
by Gavin Chipper
Sue Sanders wrote:Oh. I'd been working on this before I saw you've given an answer.

To my mind, you don't need a zero on both dice because when it's the 1st, 2nd, 3rd etc, of the month, there's no rule mentioned that says you have to display it as 01, 02, 03. So I'd just put the one relevent one out on the first 9 days of the month. So then, as long as 1,2, and 3 are on the opposite one to 0, you can do it, and it saves on dusting!

But I admit, your way is more 'tricksey'

N.B note my careful avoidance of the term dice, dices and die as I've just suffered a mind blank as to which is singular and which plural.
When I PMed Keiran, I offered two solutions: one where you don't need to use both dice for 1-9 and one where one dice covered 6 and 9.

Re: Date Dice

Posted: Sun Sep 13, 2009 11:27 pm
by Ben Hunter
Matt Morrison wrote:Image
Legend.