It’s time for the next Chalkdust Christmas Conundrum! But first it’s time to announce the lucky winners of the third conundrum competition. There were 26 entries, of which 18 were correct. The four randomly selected winners are:

- Shelby Noonan
- Jodie Fromage
- Suzie Brown
- Josh Farrant

You will all soon be proud owners of signed copies of *The Element in the Room* by Helen Arney and Steve Mould. The answer to conundrum #3 is at the bottom of this post.

The prizes up for grabs for the final conundrum are five copies of *Bletchley Park Brainteasers* by Sinclair McKay. Inspired by the prize, this conundrum builds up to a hidden message, and two of its parts involve breaking ciphers.

There are four parts to today’s conundrum. Each part has an eight digit answer. After you have found all four answers, write them out in order, then take the digits in pairs. Each pair of digits represents a letter (01 is A, 02 is B, 03 is C, and so on) and the numbers together will reveal a hidden message.

*Click here to dowload a pdf of this conundrum*

## Part 1: prime factors

The first 8 digit number has 7 (not necessarily distinct) prime factors. These factors are (in ascending order):

- An even prime number
- The smallest odd prime number
- A number whose factors add to 4
- A number that Blur, Black Sabbath, Havoc, and many others have named albums after
- The key that was used to encode the message in part 4
- The sum of four consecutive prime numbers
- The smallest prime number that is 182 more than another prime number

## Part 2: a Vigenère cipher

The second 8 digit number is **YNCSKWKZTJDGQCGTEMSVFZEBWVBFEBSZLJKWYYMZJYSURMICJYSSUPJUYSUDNWRJVL**

Hint: the key is the surname of someone we have interviewed for Chalkdust.

## Part 3: 12 days of Christmas

In the grid above, write the answers to the following questions about the song “The Twelve Days of Christmas” (write each number starting at the number of its clue and going down). Once you’ve entered all 8 clues, the red squares will reveal the third 8 digit number.

- After all 12 days, how many partridges has my true love given me?
- How many items does my true love give me on the seventh day?
- After 12 days, how many drummers drumming has my true love given me?
- After 12 days, how many items has my true love given me?
- After 12 days, how many gold rings has my true love given me?
- On which day does the total number of items that my true love has given me first exceed 150?
- After 8 days, how many items has my true love given me?
- How many items does my true love give me on the tenth day?

## Part 4: a Caesar shift

The fourth 8 digit number is **WFLIKVVEDZCCZFEFEVYLEUIVUREUKYZIKPKYFLJREUFEVYLEUIVUREUEZEVKVVE**

After you have found all four answers, write them out in order, then take the digits in pairs. Each pair of digits represents a letter (01 is A, 02 is B, 03 is C, and so on) and the numbers together will reveal a hidden message. Once you’ve found this message, enter it in the form below for a chance to win a copy of *Bletchley Park Brainteasers* by Sinclair McKay. The deadline for entering this competition is 12:00 (midday) on Friday 29 December.

*This competition is now closed*

## The solution to conundrum #3

In the third conundrum, we asked you how many solutions a nonogram puzzle has. **Stop reading now if you don’t want to know the answer yet.**

If you try to solve the nonogram, you will reach this point:

The undetermined squares have been split into three sets (red, green, and blue. Each of these has two possible solutions:

Therefore in total there are 2×2×2 options, and so the answer is **8**.