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A Sudoku that uses transformations as supporting clues.
This sudoku requires you to have "double vision" - two Sudoku's for the price of one
A Sudoku with a twist.
A Sudoku with clues as ratios.
A Sudoku with clues as ratios or fractions.
Solve this Sudoku puzzle whose clues are in the form of sums of the numbers which should appear in diagonal opposite cells.
A Sudoku with clues given as sums of entries.
This second Sudoku article discusses "Corresponding Sudokus" which are pairs of Sudokus with terms that can be matched using a substitution rule.
Two sudokus in one. Challenge yourself to make the necessary connections.
This pair of linked Sudokus matches letters with numbers and hides a seasonal greeting. Can you find it?
Four numbers on an intersection that need to be placed in the surrounding cells. That is all you need to know to solve this sudoku.
Given the products of diagonally opposite cells - can you complete this Sudoku?
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.
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.
Each clue number in this sudoku is the product of the two numbers in adjacent cells.
Each of the main diagonals of this sudoku must contain the numbers 1 to 9 and each rectangle width the numbers 1 to 4.
Solve the equations to identify the clue numbers in this Sudoku problem.
This article for teachers describes several games, found on the site, all of which have a related structure that can be used to develop the skills of strategic planning.
A particular technique for solving Sudoku puzzles, known as "naked pair", is explained in this easy-to-read article.
You need to find the values of the stars before you can apply normal Sudoku rules.
This Sudoku combines all four arithmetic operations.
Four small numbers give the clue to the contents of the four surrounding cells.
The puzzle can be solved with the help of small clue-numbers which are either placed on the border lines between selected pairs of neighbouring squares of the grid or placed after slash marks on. . . .
This Sudoku, based on differences. Using the one clue number can you find the solution?
Use the differences to find the solution to this Sudoku.
This is a variation of sudoku which contains a set of special clue-numbers. Each set of 4 small digits stands for the numbers in the four cells of the grid adjacent to this set.
Arrange the digits 1, 1, 2, 2, 3 and 3 so that between the two 1's there is one digit, between the two 2's there are two digits, and between the two 3's there are three digits.
The NRICH team are always looking for new ways to engage teachers and pupils in problem solving. Here we explain the thinking behind maths trails.
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?
Many numbers can be expressed as the sum of two or more consecutive integers. For example, 15=7+8 and 10=1+2+3+4. Can you say which numbers can be expressed in this way?
Can you use your powers of logic and deduction to work out the missing information in these sporty situations?
The challenge is to find the values of the variables if you are to solve this Sudoku.
The number of plants in Mr McGregor's magic potting shed increases overnight. He'd like to put the same number of plants in each of his gardens, planting one garden each day. How can he do it?
In this article, the NRICH team describe the process of selecting solutions for publication on the site.
Starting with four different triangles, imagine you have an unlimited number of each type. How many different tetrahedra can you make? Convince us you have found them all.
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.
Use the interactivity to listen to the bells ringing a pattern. Now it's your turn! Play one of the bells yourself. How do you know when it is your turn to ring?
A Latin square of order n is an array of n symbols in which each symbol occurs exactly once in each row and exactly once in each column.
Explore this how this program produces the sequences it does. What are you controlling when you change the values of the variables?
We're excited about this new program for drawing beautiful mathematical designs. Can you work out how we made our first few pictures and, even better, share your most elegant solutions with us?
60 pieces and a challenge. What can you make and how many of the pieces can you use creating skeleton polyhedra?
The clues for this Sudoku are the product of the numbers in adjacent squares.
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?
This Sudoku requires you to do some working backwards before working forwards.
Use the interactivity to play two of the bells in a pattern. How do you know when it is your turn to ring, and how do you know which bell to ring?
Find out what a "fault-free" rectangle is and try to make some of your own.
Try out the lottery that is played in a far-away land. What is the chance of winning?