
Pumpkin patch

Seega

Alquerque

Introducing NRICH TWILGO

Fruity totals
In this interactivity each fruit has a hidden value. Can you deduce what each one is worth?

Clocking off

Air nets

Prime magic

Like a circle in a spiral


Instant insanity
Given the nets of 4 cubes with the faces coloured in 4 colours, build a tower so that on each vertical wall no colour is repeated, that is all 4 colours appear.

Hamiltonian cube
Find the length along the shortest path passing through certain points on the cube.


Funny factorisation
Using the digits 1 to 9, the number 4396 can be written as the product of two numbers. Can you find the factors?


Triangles in the middle

Nine colours
Can you use small coloured cubes to make a 3 by 3 by 3 cube so that each face of the bigger cube contains one of each colour?

What's it worth?
There are lots of different methods to find out what the shapes are worth - how many can you find?

The bridges of Konigsberg
Investigate how networks can be used to solve a problem for the 18th Century inhabitants of Konigsberg.

Sliding puzzle

LOGO challenge - circles as animals
See if you can anticipate successive 'generations' of the two animals shown here.


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


LOGO challenge - triangles-squares-stars
Can you recreate these designs? What are the basic units? What movement is required between each unit? Some elegant use of procedures will help - variables not essential.

Triangle in a trapezium
Can you find and prove the relationship between the area of a trapezium and the area of a triangle constructed within it?

Searching for mean(ing)
If you have a large supply of 3kg and 8kg weights, how many of each would you need for the average (mean) of the weights to be 6kg?

Ding dong bell

Take three from five
Caroline and James pick sets of five numbers. Charlie tries to find three that add together to make a multiple of three. Can they stop him?


Yih or Luk tsut k'i or Three Men's Morris
Some puzzles requiring no knowledge of knot theory, just a careful inspection of the patterns. A glimpse of the classification of knots and a little about prime knots, crossing numbers and knot arithmetic.

Wipeout
Can you do a little mathematical detective work to figure out which number has been wiped out?

Shaping the universe I - planet Earth
This article explores ths history of theories about the shape of our planet. It is the first in a series of articles looking at the significance of geometric shapes in the history of astronomy.


Charting success

Sprouts

Shaping the universe II - the solar system
The second in a series of articles on visualising and modelling shapes in the history of astronomy.

Charting more success

Shaping the universe III - to infinity and beyond
The third installment in our series on the shape of astronomical systems, this article explores galaxies and the universe beyond our solar system.

Marbles in a box
How many winning lines can you make in a three-dimensional version of noughts and crosses?

What is the question?

Spots and measles
99% of people who have measles have spots. Ben has spots. Do you think he has measles?



3D treasure hunt
Some treasure has been hidden in a three-dimensional grid! Can you work out a strategy to find it as efficiently as possible?

Which is cheaper?
When I park my car in Mathstown, there are two car parks to choose from. Can you help me to decide which one to use?


Attractive tablecloths
Charlie likes tablecloths that use as many colours as possible, but insists that his tablecloths have some symmetry. Can you work out how many colours he needs for different tablecloth designs?

Speeding boats
Two boats travel up and down a lake. Can you picture where they will cross if you know how fast each boat is travelling?


Coke machine

Changing places

Slippage

Which is bigger?
Which is bigger, n+10 or 2n+3? Can you find a good method of answering similar questions?

Rectangle rearrangement




Just opposite

Painted cube
Imagine a large cube made from small red cubes being dropped into a pot of yellow paint. How many of the small cubes will have yellow paint on their faces?

Track design
Where should runners start the 200m race so that they have all run the same distance by the finish?

Around and back

In a box
Chris and Jo put two red and four blue ribbons in a box. They each pick a ribbon from the box without looking. Jo wins if the two ribbons are the same colour. Is the game fair?

Back fitter
10 graphs of experimental data are given. Can you use a spreadsheet to find algebraic graphs which match them closely, and thus discover the formulae most likely to govern the underlying processes?



Tetrahedra tester
An irregular tetrahedron is composed of four different triangles. Can such a tetrahedron be constructed where the side lengths are 4, 5, 6, 7, 8 and 9 units of length?

Triangle midpoints
You are only given the three midpoints of the sides of a triangle. How can you construct the original triangle?


Surprising transformations
I took the graph y=4x+7 and performed four transformations. Can you find the order in which I could have carried out the transformations?


Doesn't add up
In this problem we are faced with an apparently easy area problem, but it has gone horribly wrong! What happened?



Twelve cubed

Packing 3D shapes
What 3D shapes occur in nature. How efficiently can you pack these shapes together?

Kite in a square
Can you make sense of the three methods to work out what fraction of the total area is shaded?


Ladder and cube
A 1 metre cube has one face on the ground and one face against a wall. A 4 metre ladder leans against the wall and just touches the cube. How high is the top of the ladder above the ground?

Far horizon
An observer is on top of a lighthouse. How far from the foot of the lighthouse is the horizon that the observer can see?

Fermat's poser

Triangles within triangles


Gnomon dimensions

Dicey directions

Relative time

Vector walk
Starting with two basic vector steps, which destinations can you reach on a vector walk?

Isosceles seven
Is it possible to find the angles in this rather special isosceles triangle?

The spider and the fly
A spider is sitting in the middle of one of the smallest walls in a room and a fly is resting beside the window. What is the shortest distance the spider would have to crawl to catch the fly?

A problem of time

Triangles within squares

Vector journeys
Charlie likes to go for walks around a square park, while Alison likes to cut across diagonally. Can you find relationships between the vectors they walk along?

Partly circles
What is the same and what is different about these circle questions? What connections can you make?

Eulerian
Which of the five diagrams below could be drawn without taking the pen off the page and without drawing along a line already drawn?

Terminology
Given an equilateral triangle inside an isosceles triangle, can you find a relationship between the angles?

All tied up


Hypotenuse lattice points

Triangles within pentagons

Factorising with multilink
Can you find out what is special about the dimensions of rectangles you can make with squares, sticks and units?