Christmas Maths Puzzle 2017

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…

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.

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

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

If you’re interested in our book on the Maths of Christmas, it’s available by clicking on the image. US edition here.

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

28 thoughts on “Christmas Maths Puzzle 2017”

1. thomas Post author

You have 5/8 postcard clues correct. Your second comment, correcting the order, was also right.

1. Neal @zbvif

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

Neal/zbvif

2. Sara

This 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]…..?

1. thomas Post author

Thanks 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!

3. Troy

Current guesses:
rgg = REDACTED
rrg = REDACTED
ggg = REDACTED
rgr = REDACTED
ggr = REDACTED or REDACTED or REDACTED or REDACTED or REDACTED
rrr = REDACTED
grg = REDACTED
grr = REDACTED or REDACTED

Not sure how to fit them into the path yet. Also not sure how to get REDACTED yet — the presents or their numeric values in binary, perhaps — but 3 into 25 isn’t an integer. {facepalm}

1. thomas Post author

You 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!

4. William

Okay, need help. Am I close?
R – G – G: REDACTED
R – R – G: REDACTED
G – G – G: REDACTED
R – G – R: REDACTED
G – G – R: REDACTED? REDACTED?
R – R – R: REDACTED
G – R – G: REDACTED?
G – R – R: REDACTED?? WHAT DOES THIS MEAN?

1. thomas Post author

You’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!

5. Alex Rennie

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

Postcards in the order I think is right:
REDACTED
REDACTED
REDACTED(could be REDACTED?)
REDACTED
REDACTED (because of REDACTED)
REDACTED
REDACTED (and REDACTED?)
REDACTED

Because of the REDACTED I also think the present trail is REDACTED. The only words I could see in there were REDACTED but that doesn’t help me either.

So definitely stuck! Any clues for me?
Thanks!

1. thomas Post author

You 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.

1. Alex Rennie

Ok – thanks! On looking at the new clues I think it’s to do with REDACTED. Maybe REDACTED of that?

Am I anywhere near? Or barking up the wrong tree?

1. Alex Rennie

Great puzzle – it’s driving me mad!

Here’s what I’ve tried:
a) REDACTED

b) REDACTED

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

2. thomas Post author

I 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.)

1. thomas Post author

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

6. Andy

More confused with 2nd clues 🙂
REDACTED REDACTED REDACTED REDACTED REDACTED REDACTED REDACTED REDACTED
REDACTED REDACTED REDACTED REDACTED REDACTED REDACTED

1. thomas Post author

Hmm, 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!)…

7. Heather Dudek

For the first set I got:
REDACTED

The second set:
REDACTED

I’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!

1. thomas Post author

You’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!

1. Heather Dudek

I think I’m stuck on clue 4 – unless it’s just REDACTED? Then it’s REDACTED, which I can see is REDACTED. The remaining part REDACTED except REDACTED. I still feel like I’m missing part and can’t completely “show my work”!

(I also tried to convert REDACTED to numeric, which is conveniently REDACTED, but then what to do with this huge number…)

1. thomas Post author

Argh, 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.

8. Neal @zbvif

Still not getting it. I think we have
REDACTED

REDACTED is pure guess following REDACTED. No real answer to either clue. Maybe REDACTED. Clock clue shows either REDACTED or REDACTED, suggesting that clone is REDACTED.

Cannot get a link from REDACTED to REDACTED.

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

1. thomas Post author

You 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.