Working Systematically - Upper Secondary

Charlie's Delightful Machine

Stage: 3 and 4 Challenge Level: Challenge Level:1

Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?

Peaches Today, Peaches Tomorrow....

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

Whenever a monkey has peaches, he always keeps a fraction of them each day, gives the rest away, and then eats one. How long could he make his peaches last for?

What's Possible?

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

Many numbers can be expressed as the difference of two perfect squares. What do you notice about the numbers you CANNOT make?

A Long Time at the Till

Stage: 4 and 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Try to solve this very difficult problem and then study our two suggested solutions. How would you use your knowledge to try to solve variants on the original problem?

Sorted

Stage: 5 Challenge Level: Challenge Level:1

How can you quickly sort a suit of cards in order from Ace to King?

Adding Machine

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

Can you set the logic gates so that this machine can decide how many bulbs have been switched on?

Ante Up

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

Use cunning to work out a strategy to win this game.

Stage 5 Cipher Challenge

Stage: 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?

No Square Sums

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 12 - 2011
How many numbers do you need to remove to avoid making a perfect square?

Spead Out

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 24 - 2015
In how many ways can you move through the grid to give the digits 2009?

Nine Colours

Stage: 3 and 4 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

You have 27 small cubes, 3 each of nine colours. Use the small cubes to make a 3 by 3 by 3 cube so that each face of the bigger cube contains one of every colour.

Rolling Along the Trail

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 32 - 2011
What could be the scores from five throws of this dice?

Phone Call

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 25 - 2015
How many different phone numbers are there starting with a 3 and with at most two different digits?

Gridlines

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 27 - 2015
How many triples of points are there in this 4x4 array that lie on a straight line?

Medal Ceremony

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 41 - 2013
The teacher has forgotten which pupil won which medal. In how many different ways could he give the medals out to the pupils?

Switch On

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 39 - 2015
In how many different ways can a row of five "on/off" switches be set so that no two adjacent switches are in the "off" position?

Amazing

Stage: 3 and 4 Short Challenge Level: Challenge Level:2 Challenge Level:2

Weekly Problem 6 - 2014
A maze has nine rooms, with gaps in the walls between them. How many ways are there to travel from X to Y?

Wedding Morning

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 45 - 2015
If Sam is getting married on the 9th of November 2015 aged 30, do you know which year Pat was born in?

Fiction in Wonderland

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 17 - 2014
Tweedledum, Tweedledee, Alice and the White Rabbit are having a conversation. How many of the statements they make are true?

Middle Digit Mean

Stage: 3 and 4 Short Challenge Level: Challenge Level:2 Challenge Level:2

Weekly Problem 16 - 2016
How many three digit numbers have the property that the middle digit is the mean of the other two digits?

Circle of Lies

Stage: 3 and 4 Short Challenge Level: Challenge Level:2 Challenge Level:2

Weekly Problem 34 - 2014
Can you work out how many of Pierre, Qadr, Ratna, Sven and Tanya are telling the truth?

Domino Hexagon

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 18 - 2017
Dominic wants to place the six dominoes above in a hexagonal ring. Which of the dominoes could be placed next to the one shown?

Mini-sodoku

Stage: 3 and 4 Short Challenge Level: Challenge Level:1

Weekly Problem 8 - 2015
How many ways are there of completing the mini-sudoku shown?