Welcome to mscroggs.co.uk

The next door (door 12) will open in approximately 5 hours and 8 minutes.

Enter your email address here to be emailed a magic link to synchronise your answers across mutiple computers:

It's nearly Christmas and something terrible has happened: there's been a major malfunction in multiple machines in Santa's toy factory, and not enough presents have been made. Santa has a backup warehouse full of wrapped presents that can be used in the case of severe emergency, but the warehouse is locked. You need to help Santa work out the code to unlock the warehouse so that he can deliver the presents before Christmas is ruined for everyone.

The information needed to work out the code to the warehouse is known by Santa and his three most trusted elves: Santa is remembering a three-digit number, and each elf is remembering a one-digit and a three-digit number. If Santa and the elves all agree that the emergency warehouse should be opened, they can work out the code for the door as follows:

But this year, there is a complication: the three elves are on a diplomatic mission to Mars to visit Martian Santa and cannot be contacted, so you need to piece together their numbers from the clues they have left behind.

Behind each day (except Christmas Day), there is a puzzle with a three-digit answer. Each of these answers forms part of a clue about Santa's and the elves' numbers. You must use these clues to work out the code for the warehouse. You can use this page to try opening the door. If you enter an incorrect code three times, the door mechanism locks until the following day.

Ten randomly selected people who solve all the puzzles, open the warehouse, and fill in the entry form behind the door on the 25th will win prizes!

The prizes will include an mscroggs.co.uk Advent 2024 T-shirt. If you'd like one of the T-shirts from a previous Advent, they are available to order at merch.mscroggs.co.uk.

The winners will be randomly chosen from all those who submit the entry form before the end of 2024. 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 information about this competition in this blog post. If you'd like to chat with other solvers, we'll be discussing the Advent Calendar in the #scroggs-advent-calendar channel in the Finite Group Discord: you can join the Discord by following the link in this post on Patreon (you'll need to become a free member on Patreon to unlock the 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.