Pentagram Pylons - can you elegantly recreate them? Or, the European flag in LOGO - what poses the greater problem?
Explore this how this program produces the sequences it does. What are you controlling when you change the values of the variables?
Read this article to find out more about the inspiration for NRICH's game, Phiddlywinks.
This second Sudoku article discusses "Corresponding Sudokus" which are pairs of Sudokus with terms that can be matched using a substitution rule.
Remember that you want someone following behind you to see where you went. Can yo work out how these patterns were created and recreate them?
A pair of Sudokus with lots in common. In fact they are the same problem but rearranged. Can you find how they relate to solve them both?
This sudoku requires you to have "double vision" - two Sudoku's for the price of one
A Sudoku based on clues that give the differences between adjacent cells.
In this article, the NRICH team describe the process of selecting solutions for publication on the site.
In this Sudoku, there are three coloured "islands" in the 9x9 grid. Within each "island" EVERY group of nine cells that form a 3x3 square must contain the numbers 1 through 9.
Special clue numbers related to the difference between numbers in two adjacent cells and values of the stars in the "constellation" make this a doubly interesting problem.
Take three whole numbers. The differences between them give you three new numbers. Find the differences between the new numbers and keep repeating this. What happens?
in how many ways can you place the numbers 1, 2, 3 … 9 in the nine regions of the Olympic Emblem (5 overlapping circles) so that the amount in each ring is the same?
Find all the ways of placing the numbers 1 to 9 on a W shape, with 3 numbers on each leg, so that each set of 3 numbers has the same total.
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.
Just four procedures were used to produce a design. How was it done? Can you be systematic and elegant so that someone can follow your logic?
Label the joints and legs of these graph theory caterpillars so that the vertex sums are all equal.
Imagine you have an unlimited number of four types of triangle. How many different tetrahedra can you make?
You are given the Lowest Common Multiples of sets of digits. Find the digits and then solve the Sudoku.
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.
Advent Calendar 2011 - a mathematical activity for each day during the run-up to Christmas.
Four friends must cross a bridge. How can they all cross it in just 17 minutes?
Make your own double-sided magic square. But can you complete both sides once you've made the pieces?
Time for a little mathemagic! Choose any five cards from a pack and show four of them to your partner. How can they work out the fifth?
Gabriel multiplied together some numbers and then erased them. Can you figure out where each number was?
Given the products of diagonally opposite cells - can you complete this Sudoku?
A Sudoku with clues as ratios.
My two digit number is special because adding the sum of its digits to the product of its digits gives me my original number. What could my number be?
In this game you are challenged to gain more columns of lily pads than your opponent.
This Sudoku puzzle can be solved with the help of small clue-numbers on the border lines between pairs of neighbouring squares of the grid.
Can you use your powers of logic and deduction to work out the missing information in these sporty situations?
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?
You need to find the values of the stars before you can apply normal Sudoku rules.
A pair of Sudoku puzzles that together lead to a complete solution.
Move your counters through this snake of cards and see how far you can go. Are you surprised by where you end up?
How many different symmetrical shapes can you make by shading triangles or squares?
If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?
60 pieces and a challenge. What can you make and how many of the pieces can you use creating skeleton polyhedra?
Can you arrange the numbers 1 to 17 in a row so that each adjacent pair adds up to a square number?
Use the differences to find the solution to this Sudoku.
Four small numbers give the clue to the contents of the four surrounding cells.
A Sudoku with clues as ratios.
A monkey with peaches, keeps a fraction of them each day, gives the rest away, and then eats one. How long can his peaches last?
Find out about Magic Squares in this article written for students. Why are they magic?!
Draw some isosceles triangles with an area of $9$cm$^2$ and a vertex at (20,20). If all the vertices must have whole number coordinates, how many is it possible to draw?
There is a long tradition of creating mazes throughout history and across the world. This article gives details of mazes you can visit and those that you can tackle on paper.
Charlie and Abi put a counter on 42. They wondered if they could visit all the other numbers on their 1-100 board, moving the counter using just these two operations: x2 and -5. What do you think?
This Sudoku, based on differences. Using the one clue number can you find the solution?
An extra constraint means this Sudoku requires you to think in diagonals as well as horizontal and vertical lines and boxes of nine.
The puzzle can be solved by finding the values of the unknown digits (all indicated by asterisks) in the squares of the $9\times9$ grid.