Click here to win prizes by solving the puzzle Advent calendar.
Click here to win prizes by solving the puzzle Advent calendar.


Welcome to

It's nearly Christmas and something terrible has happened: while out on a test flight, Santa's sled was damaged and Santa, Rudolph and Blitzen fell to the ground over the Advent Isles. You need to find Santa and his reindeer before Christmas is ruined for everyone.
You have gathered one inhabitant of the four largest Advent Isles—Rum, Land, Moon and County—and they are going to give you a series of clues about where Santa and his reindeer landed. However, one or more of the islanders you have gathered may have been involved in damaging Santa's sled and causing it to crash: any islander involved in this will lie to you to attempt to stop you from finding Santa and his reindeer. Once you are ready to search for Santa, Rudolph and Blitzen, you can find the map by following this link.
Each of the clues will be about Santa's, Rudolph's or Blitzen's positions in Advent Standard Coordinates (ASC): ASC are given by six two-digit numbers with dots inbetween, for example For this example coordinate, the islanders will refer to (the first) 12 as the first coordinate, 52 as the second coordinate, (the second) 12 as the third coordinate, 13 as the fourth coordinate, 84 as the fifth coordinate, and 55 as the sixth coordinate.
To find a point's ASC coordinates, split a map of the islands into a 9×9 grid, then number the rows and columns 1 to 9: the first two digits of ASC give the vertical then horizontal position of a square in this grid. The next two digits then give a smaller square when this square is then itself split into a 9×9 grid, and so on. An example is show below.
The ASC coordinates of this pair of flowers are (click to enlarge).
Behind each day (except Christmas Day), there is a puzzle with a three-digit answer. Each of these answers forms part of a fact that one of the islanders tells you. You must use these clues to find Santa and his two reindeer.
Ten randomly selected people who solve all the puzzles and submit their answers to the logic puzzle using the form behind the door on the 25th will win prizes!
The winners will be randomly chosen from all those who submit their answers before the end of 2019. Each day's puzzle (and the entry form on Christmas Day) will be available from 5:00am GMT. But as the winners will be selected randomly, there's no need to get up at 5am on Christmas Day to enter!
You can find more infomation about this competition, in this blog post.
On this website, you can find my blog and a collection of puzzles. You can also find details of my academic work and information about pop maths and outreach talks that I give. You can use this handy tool to help you decide what to do first.
Recent blogs (click to read).
My most recent blog post is Christmas card 2019. Other highlights of the blog include:
If you're not sure where to start, you could try reading a random article or taking a suggestion from this handy tool.

Recent puzzles (click to read).
New puzzles are posted on many Sundays, with answers posted on Monday. The most recent collection is Sunday Afternoon Maths LXVII.
Some of my favourite puzzles are:
Every December, I post an Advent calendar full of puzzles. You can view the puzzles from the 2018 calendar here. You can view this year's Advent calendar by scrolling up.
Again, a random puzzle or a suggestion from this handy tool could be good places to start.

 Who am I? 
My face.
I am Matthew Scroggs. I like maths.
I currently a postdoctoral research associate in the Department of Engineering at the University of Cambridge. Before this, I did a PhD in the Department of Mathematics at UCL and before that I obtained a Master's degree in mathematics at the University of Oxford. Between Oxford and UCL, I worked as a maths teacher in a secondary school. During my PhD, I began working on the open source boundary element method library Bempp. During my postdoc at Cambridge, I began working on the open source finite element library FEniCS. You can find more about my work on the academic page.
You can regularly find me at London MathsJam (second last Tuesday of the month), the MathsJam Gathering (yearly) and EMF Camp (every two years). I write the crossnumber (as Humbug), puzzles and articles for Chalkdust Magazine. For more non-work related articles and talks, see the talks page.
If you would like to reuse any of my content, please get in touch.

Some numbers

 I have written 71 blog posts.
 I have posted 264 puzzles.
 I have published 4 papers (and submitted 2 more).
 I have tweeted 5073 tweets.
 I have tooted 91 toots.
 I have 48 public repositories on GitHub.
 I have contributed 12 sequences to the OEIS.
 I have written 2 LaTeΧ packages.
 I have 146 reputation on Math Stack Exchange.
 I have solved 122 problems on Project Euler.
 I have run 27 parkruns.
 I have run 9 half marathons, and 1 marathon.
 I have found 70 geocaches.
 My Erdős number is 6.
 My Bacon number is ∞.
 My Sabbath number is ∞.
 My Erdős–Bacon number is ∞.
 My Erdős–Bacon–Sabbath number is ∞.
© Matthew Scroggs 2012–2019