**SOLUTION NOW AVAILABLE! – CLICK HERE**

*If you enjoy Maths and Christmas (and how could you not?), **you **might be interested in the new edition of the book I wrote with Hannah Fry: “The Indisputable Existence of Santa Claus”.
(Or maybe you would prefer the US edition)*

**Rudolph has been kidnapped!**

Santa could hardly believe his eyes when he awoke this morning to find that the leader of his sleigh was missing from Lapland’s luxury reindeer stables.

Santa knows one of his 7 elves (conveniently named One, Two, Three, Four, Five, Six and Seven) must be responsible, but which one? *****

Luckily a mystery ally seems to have left him a few clues to go on…

The first is this trail of presents, left in the snow. The red presents seem to be full, but the green ones are empty…

*(To see a colour-blind friendly version of these images, click HERE)*

Santa has also received these eight curious postcards. Could they also be clues? Unfortunately, they have become mixed up in the post, so he’s not sure what order they go in.

**[A few days later, Santa received some more postcards! Click here to see them.]**

The stakes are high. Without Rudolph, there is no way Santa will be able to deliver presents to the world’s children on Christmas Eve.

**Can you work out which elf is responsible?**

**Please submit solutions/partial solutions/cries for help
**

**on this page**

**via the comments below.**

**CLICK HERE FOR THE SOLUTION**

*And in case you didn’t see it last year, you can catch up with
our 2016 Advent Calendar of Christmas maths puzzles *

**HERE**

*.*

*** **Of course, this is not the first time that one of the elves has engaged in criminal activity…

Matt[CORRECT SOLUTION – REPRODUCED ON SOLUTION PAGE]Neal[Edited to avoid spoilers]thomasPost authorYou have 5/8 postcard clues correct. Your second comment, correcting the order, was also right.

Neal @zbvifAs an aside. Your colour blind version has black and white boxes, but still describes red boxes as full, and green as empty

Neal/zbvif

thomasPost authorThanks for pointing this out. Now sorted.

SaraThis is really hard!

I’m not giving up though.

[REDACTED]and[REDACTED]for the first two as a start?I’m then working on

[REDACTED],[REDACTED],[REDACTED]and[REDACTED]…..?thomasPost authorThanks for having a go!

You have 4/8 for the postcard clues, so far.

I’ll put some more clues up tomorrow (though there is enough to solve it now, of course!).

Good luck!

TroyCurrent guesses:

rgg =

REDACTEDrrg =

REDACTEDggg =

REDACTEDrgr =

REDACTEDggr =

REDACTEDorREDACTEDorREDACTEDorREDACTEDorREDACTEDrrr =

REDACTEDgrg =

REDACTEDgrr =

REDACTEDorREDACTEDNot sure how to fit them into the path yet. Also not sure how to get

REDACTEDyet — the presents or their numeric values in binary, perhaps — but 3 into 25 isn’t an integer. {facepalm}thomasPost authorYou have 5/8 clues correct. You’re going for too many numbers…

I’ll put some other clues up tomorrow (alternative clues for each of the postcards).

Thanks for having a go!

WilliamOkay, need help. Am I close?

R – G – G:

REDACTEDR – R – G:

REDACTEDG – G – G:

REDACTEDR – G – R:

REDACTEDG – G – R:

REDACTED?REDACTED?R – R – R:

REDACTEDG – R – G:

REDACTED?G – R – R:

REDACTED?? WHAT DOES THIS MEAN?thomasPost authorYou’ve pretty much got 5.5/8 of the postcard clues correct.

You need to think about what order they go in also.

Good luck!

Alex RennieHi! I’m stuck now, but this is what I have…

Postcards in the order I think is right:

REDACTEDREDACTEDREDACTED(could beREDACTED?)REDACTEDREDACTED(because ofREDACTED)REDACTEDREDACTED(andREDACTED?)REDACTEDBecause of the

REDACTEDI also think the present trail isREDACTED. The only words I could see in there wereREDACTEDbut that doesn’t help me either.So definitely stuck! Any clues for me?

Thanks!

thomasPost authorYou have 7/8 postcard clues correct, and the right order. Perhaps compare against the alternative postcard clues that went up today. You’re missing the meaning of some of them though, so you’re missing a crucial stage in the solution.

Alex RennieOk – thanks! On looking at the new clues I think it’s to do with

REDACTED. MaybeREDACTEDof that?Am I anywhere near? Or barking up the wrong tree?

thomasPost authorPerhaps have a go and find out…

Alex RennieGreat puzzle – it’s driving me mad!

Here’s what I’ve tried:

a)

REDACTEDb)

REDACTEDSo my question is: should I keep trying on a) or b) or start again?

thomasPost authorI like one of those two approaches. I think you should try it again, though, because I don’t agree with your result! I wonder whether you have understood the meaning of the fourth clue?

(I would worry that I’d made a mistake with the puzzle, but happily I have seen someone solve it correctly.)

Andyroughly

REDACTEDthomasPost authorYou have 6.5/8 postcard clues correct and the right order. Perhaps compare with the alternative clues that went up today.

AndyMore confused with 2nd clues 🙂

REDACTEDREDACTEDREDACTEDREDACTEDREDACTEDREDACTEDREDACTEDREDACTEDREDACTEDREDACTEDREDACTEDREDACTEDREDACTEDREDACTED…thomasPost authorHmm, well your first postcard clue suggestions were pretty much perfect.

Not sure what’s going on in the second line (though it certainly starts well!)…

Heather DudekFor the first set I got:

REDACTEDThe second set:

REDACTEDI’m thinking the order should be based off

REDACTED, so combining the two sets it’s something like:REDACTED, but I’m still missing something. I admit my math is rusty so that might be the missing link! I’ll keep working at it. Fun diversion!thomasPost authorYou’re basically absolutely right! It does indeed require the application of a particular mathematical ‘tool’, though.

You need to know what the first three clues mean when put together as you have done, then what the fourth means in the context of the first three. Then you can apply some of the other clues, and interpret with the one that remains.

Well done so far!

Heather DudekI think I’m stuck on clue 4 – unless it’s just

REDACTED? Then it’sREDACTED, which I can see isREDACTED. The remaining partREDACTEDexceptREDACTED. I still feel like I’m missing part and can’t completely “show my work”!(I also tried to convert

REDACTEDto numeric, which is convenientlyREDACTED, but then what to do with this huge number…)thomasPost authorArgh, you’re so close!

You need to understand what clue 4 (say what you see) means in the context of clues 1-3. Also, you’re not applying what you (correctly) understand of clues 1-3 in the right way. Think about how else you could apply it.

Very, very close though.

Neal @zbvifStill not getting it. I think we have

REDACTEDREDACTEDis pure guess followingREDACTED. No real answer to either clue. MaybeREDACTED. Clock clue shows eitherREDACTEDorREDACTED, suggesting that clone isREDACTED.Cannot get a link from

REDACTEDtoREDACTED.And then there are 25 presents in the snow. Not

REDACTED, afaik. Binary could be anything.REDACTED. No help.Doubt i am going to solve this.

Interesting though.

Neal

thomasPost authorYou are quite close. As you acknowledge, you have 7/8 clues correct and you have written the correct answer for the 8th clue elsewhere in your response. You would then need to know what the first three clues mean when put together (and then what the fourth means in that context). If you got that far, you would likely see how to solve it from there.

Neal zbvif[CORRECT SOLUTION – REPRODUCED ON SOLUTION PAGE]