The solutions to the imp and pixie puzzles are below.

# New Year Puzzles

**Happy New Year!**

So, the Elfnigma (**Puzzle**, **Solution**) that was set as Day 9 of the Mathematical Advent Calendar suggests some further chess board related puzzles featuring other varieties of faerie folk. Obviously, the elves of the puzzle were based on queens from a chessboard, but while queens can take any piece in the same row, column or diagonal, elves could only see tiles in these directions that were either adjacent (diagonally, horizontally or vertically) or of the same colour.

The question asked was (essentially) how many elves could be placed on a chess board, such that none could see any other (just as the Eight Queens Problem asks how eight queens can be placed on a chess board such that none threatens any other). This leads naturally to other questions involving magical creatures that are based on other chess pieces. Continue reading

# Happy Boxing Day from The Indisputable Santa Mathematical Advent Calendar!

**Happy Boxing Day!**

**Throughout the month, to accompany the release of our book on the Mathematics of Christmas, Hannah Fry & I were tweeting out Christmathsy bits and pieces, one a day, advent calendar style.**

A final post, to provide the solution to Friday’s puzzle.

# Merry Christmas from The Indisputable Santa Mathematical Advent Calendar!

**Merry Christmas!**

**Throughout the month, to accompany the release of our book on the Mathematics of Christmas, Hannah Fry & I were tweeting out Christmathsy bits and pieces, one a day, advent calendar style.**

Thanks for following the Indisputable Santa Mathematical Advent Calendar. Just a few loose ends to wrap up, with a solution to our Christmas Eve puzzle today, with the solution to Friday’s puzzle (Santa’s Dressing Room Disasters) to come tomorrow…

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The Indisputable Santa Mathematical Advent Calendar

Day 24

**Happy 24th of December!**

**Throughout the month, to accompany the release of our book on the Mathematics of Christmas, Hannah Fry & I are tweeting out Christmathsy bits and pieces, one a day, advent calendar style. Assuming we don’t run out of ideas, that is…**

And so, the final day of the Impossible Santa Mathematical Advent Calendar has arrived. Santa is about to set off, but there’s still time to take a quick register of the reindeer:

**“Now, Dasher! Now, Dancer! Now, Prancer, and Vixen!**

**“On, Comet! On, Cupid! On, Donner and Blitzen!”***

But, wait a minute… Which one is which?

Answers via the comments or on Twitter. All correct answers will be rewarded with deep respect and warm Christmas wishes. Enjoy!

The solution to this puzzle will be posted tomorrow (Christmas!) with the solution to yesterday’s Dressing Room Disaster puzzles to follow on Boxing Day (mainly because the explanation of the solution is taking a while to write up!).

Merry Christmas everyone!

**CLICK HERE TO SEE THE COMPLETE CALENDAR**

***** I was interested to learn that “Donner and Blitzen” were actually named “Dunder and Blixen” (or other variations thereof) in early versions of the text. I suppose the versions in Rudolph the Red-Nosed Reindeer must have ultimately overwhelmed these alternatives.

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The Indisputable Santa Mathematical Advent Calendar

Day 23

**Happy 23rd of December!**

**Throughout the month, to accompany the release of our book on the Mathematics of Christmas, Hannah Fry & I are tweeting out Christmathsy bits and pieces, one a day, advent calendar style. Assuming we don’t run out of ideas, that is…**

We’re getting to the business end of this advent calendar now and the puzzling is getting serious. High stakes stuff today, as Santa needs help getting into that iconic costume…

Two levels of challenge…

Merry:

And Mayhem!

(For the advanced puzzle, note that not every path starting and ending in A involves a complete circuit of the pole. For example, if Santa follows the path ABCDBA, he has not completed a circuit.)

Each time you enter a room, you MUST follow all of the instructions written there.

For extra credit, try to find Santa’s shortest possible path in each case. And for *extra* extra credit, prove that your path really is the shortest.

Answers via the comments or on Twitter. All correct answers will be rewarded with deep respect and warm Christmas wishes.

The answers for these two puzzles won’t be available until Boxing Day, so you have an extra couple of days to think about them.

And join us tomorrow for the final day of the Impossible Santa Mathematical Advent Calendar!

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The Indisputable Santa Mathematical Advent Calendar

Day 22

**Happy 22nd of December!**

**Throughout the month, to accompany the release of our book on the Mathematics of Christmas, Hannah Fry & I are tweeting out Christmathsy bits and pieces, one a day, advent calendar style. Assuming we don’t run out of ideas, that is…**

You may remember from Day 10 that Santa is not all that good with passwords and security. Well…

Here’s the letter in copyable form:

**05-06-02-19 20-02-15-21-02. 17-13-06-02-20-06 04-16-22-13-05 26-16-22 03-19-10-15-08 14-06 02 ~**MESSAGE~CORRUPTED**~ 6765-10946-8-233-233-1-10946-8-5 55-3-987-6765-1-34-8-5-4181-987-610. 10946-34-1-610-144 121393-987-17711. 1-1-4181-1 (1-21-8-5 8)**

Answers via the comments or on Twitter. All correct answers will be rewarded with deep respect and warm Christmas wishes. Enjoy!

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The Indisputable Santa Mathematical Advent Calendar

Day 21

**Happy 21st of December!**

Today, we’re investigating a crime…

Answers via the comments or on Twitter. All correct answers will be rewarded with deep respect and warm Christmas wishes. Enjoy!

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The Indisputable Santa Mathematical Advent Calendar

Day 20

**Happy 20th of December!**

OK, since the upcoming final four puzzles of the calendar may be a little tough, today, some light relief…

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The Indisputable Santa Mathematical Advent Calendar

Day 19

**Happy 19th of December!**