# Puzzles

## 25 December

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

**12.52.12.13.84.55**. 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.Here are the clues:

3

Rum says: "The product of all the digits in Blitzen's six coords is **432**."

21

Moon says: "Blitzen's fifth coord is **23**."

9

Moon says: "Blitzen's third coord is **23**."

1

Land says: "Santa's third coord ends in **3**,

**0**or

**1**."

2

Land says: "Santa's third coord ends in **2**,

**0**or

**3**."

4

Rum says: "Santa's second coord ends in **3**,

**4**or

**1**."

12

Rum says: "Rudolph's second and sixth coords are both **64**."

10

Rum says: "All six of Rudolph's coords are factors of **256**."

18

Moon says: "Santa's fourth and fifth coords are both **79**."

24

County says: "Santa's third coord ends in **3**,

**2**or

**1**."

22

Land says: "Santa's sixth coord is not **43**."

7

Rum says: "Santa's sixth coord is **43**."

23

County says: "One of the digits of Santa's third coord is **7**."

25

✔14

Land says: "Santa's third coord is **12**."

5

Rum says: "Santa's first coord is **36**."

15

Rum says: "Blitzen's first coord is **23**."

17

Rum says: "The first digit of Santa's third coord is **1**."

8

County says: "Santa's third coord shares a factor (≠1) with **270**."

6

County says: "Santa's second coord is **21**."

16

Land says: "Blitzen's second coord is **21**."

20

Moon says: "All six of Rudolph's coords are multiples of **8**."

11

Moon says: "The sum of Rudolph's six coords is **192**."

13

Moon says: "Santa's second coord is **21**or

**11**."

19

Moon says: "Blitzen's fourth and sixth coords are both **11**."

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.

You can view the map here.

## 24 December

There are six 3-digit numbers with the property that the sum of their digits is equal to the product of their digits. Today's number is the largest of these numbers.

## 23 December

Arrange the digits 1-9 in a 3×3 square so the 3-digits numbers formed in the rows and columns are the types of numbers given at the ends of the rows and columns.
The number in the first column is today's number.

a multiple of 4 | |||

a cube | |||

a multiple of 3 | |||

today's number | a cube | an odd number |

## 22 December

In bases 3 to 9, the number 112 is:
\(11011_3\),
\(1300_4\),
\(422_5\),
\(304_6\),
\(220_7\),
\(160_8\), and
\(134_9\).
In bases 3, 4, 6, 8 and 9, these representations contain no digit 2.

There are two 3-digit numbers that contain no 2 in their representations in all the bases between 3 and 9 (inclusive). Today's number is the smaller of these two numbers.

## 21 December

Put the digits 1 to 9 (using each digit exactly once) in the boxes so that the sums are correct. The sums should be read left to right and top to bottom ignoring the usual order of operations. For example, 4+3×2 is 14, not 10.
Today's number is the smallest number you can make with the digits in the red boxes.

+ | - | = 7 | |||

÷ | - | ÷ | |||

+ | ÷ | = 8 | |||

× | × | × | |||

+ | - | = 7 | |||

= 12 | = 5 | = 28 |

## 20 December

The integers from 2 to 14 (including 2 and 14) are written on 13 cards (one number per card). You and a friend take it in turns to take one of the numbers.

When you have both taken five numbers, you notice that the product of the numbers you have collected is equal to the product of the numbers that your friend has collected.
What is the product of the numbers on the three cards that neither of you has taken?

## 19 December

The diagram below shows three squares and five circles.
The four smaller circles are all the same size, and the red square's vertices are the centres of these circles.

The area of the blue square is 14 units. What is the area of the red square?

## 18 December

The final round of game show starts with £1,000,000. You and your opponent take it in turn to take any value between £1 and £900.
At the end of the round, whoever takes the final pound gets to take the money they have collected home, while the other player leaves with nothing.

You get to take an amount first. How much money should you take to be certain that you will not go home with nothing?