Solve the equations to identify the clue numbers in this Sudoku problem.
A Sudoku with a twist.
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.
Four numbers on an intersection that need to be placed in the
surrounding cells. That is all you need to know to solve this
You need to find the values of the stars before you can apply normal Sudoku rules.
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.
Label this plum tree graph to make it totally magic!
You have twelve weights, one of which is different from the rest.
Using just 3 weighings, can you identify which weight is the odd
one out, and whether it is heavier or lighter than the rest?
The challenge is to find the values of the variables if you are to
solve this Sudoku.
You are given the Lowest Common Multiples of sets of digits. Find
the digits and then solve the 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.
Pentagram Pylons - can you elegantly recreate them? Or, the
European flag in LOGO - what poses the greater problem?
Use the differences to find the solution to this Sudoku.
This second Sudoku article discusses "Corresponding Sudokus" which are pairs of Sudokus with terms that can be matched using a substitution rule.
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.
A Sudoku with clues as ratios.
Problem solving is at the heart of the NRICH site. All the problems
give learners opportunities to learn, develop or use mathematical
concepts and skills. Read here for more information.
Four small numbers give the clue to the contents of the four
Remember that you want someone following behind you to see where
you went. Can yo work out how these patterns were created and
This Sudoku, based on differences. Using the one clue number can you find the solution?
Given the products of diagonally opposite cells - can you complete
Label the joints and legs of these graph theory caterpillars so that the vertex sums are all equal.
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.
This pair of linked Sudokus matches letters with numbers and hides a seasonal greeting. Can you find it?
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?
A pair of Sudoku puzzles that together lead to a complete solution.
Just four procedures were used to produce a design. How was it
done? Can you be systematic and elegant so that someone can follow
A Sudoku that uses transformations as supporting clues.
A Sudoku with clues as ratios or fractions.
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
This Sudoku combines all four arithmetic operations.
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?
A Sudoku with clues given as sums of entries.
A particular technique for solving Sudoku puzzles, known as "naked pair", is explained in this easy-to-read article.
Each of the main diagonals of this sudoku must contain the numbers
1 to 9 and each rectangle width the numbers 1 to 4.
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?
This Sudoku requires you to do some working backwards before working forwards.
Two sudokus in one. Challenge yourself to make the necessary
How have "Warmsnug" arrived at the prices shown on their windows? Which window has been given an incorrect price?
Each clue number in this sudoku is the product of the two numbers in adjacent cells.
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
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?
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.
Find out about Magic Squares in this article written for students. Why are they magic?!