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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.

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Find the smallest whole number which, when mutiplied by 7, gives a product consisting entirely of ones.

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This Sudoku requires you to do some working backwards before working forwards.

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Given the products of diagonally opposite cells - can you complete this Sudoku?

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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.

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This Sudoku, based on differences. Using the one clue number can you find the solution?

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A student in a maths class was trying to get some information from her teacher. She was given some clues and then the teacher ended by saying, "Well, how old are they?"

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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?

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Ben, Jack and Emma passed counters to each other and ended with the same number of counters. How many did they start with?

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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. . . .

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The items in the shopping basket add and multiply to give the same amount. What could their prices be?

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Place the 16 different combinations of cup/saucer in this 4 by 4 arrangement so that no row or column contains more than one cup or saucer of the same colour.

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Two sudokus in one. Challenge yourself to make the necessary connections.

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.

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Replace the letters with numbers to make the addition work out correctly. R E A D + T H I S = P A G E

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An extra constraint means this Sudoku requires you to think in diagonals as well as horizontal and vertical lines and boxes of nine.

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Four small numbers give the clue to the contents of the four surrounding cells.

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A few extra challenges set by some young NRICH members.

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Use the differences to find the solution to this Sudoku.

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The letters of the word ABACUS have been arranged in the shape of a triangle. How many different ways can you find to read the word ABACUS from this triangular pattern?

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This pair of linked Sudokus matches letters with numbers and hides a seasonal greeting. Can you find it?

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The clues for this Sudoku are the product of the numbers in adjacent squares.

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A cinema has 100 seats. Show how it is possible to sell exactly 100 tickets and take exactly Â£100 if the prices are Â£10 for adults, 50p for pensioners and 10p for children.

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Mr Smith and Mr Jones are two maths teachers. By asking questions, the answers to which may be right or wrong, Mr Jones is able to find the number of the house Mr Smith lives in... Or not!

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A pair of Sudoku puzzles that together lead to a complete solution.

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You need to find the values of the stars before you can apply normal Sudoku rules.

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Play the divisibility game to create numbers in which the first two digits make a number divisible by 2, the first three digits make a number divisible by 3...

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Rather than using the numbers 1-9, this sudoku uses the nine different letters used to make the words "Advent Calendar".

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Given the products of adjacent cells, can you complete this Sudoku?

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A game for 2 people. Take turns placing a counter on the star. You win when you have completed a line of 3 in your colour.

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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.

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Can you find six numbers to go in the Daisy from which you can make all the numbers from 1 to a number bigger than 25?

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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?

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Gabriel multiplied together some numbers and then erased them. Can you figure out where each number was?

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By selecting digits for an addition grid, what targets can you make?

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In this game you are challenged to gain more columns of lily pads than your opponent.

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Can you use your powers of logic and deduction to work out the missing information in these sporty situations?

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Can you arrange the numbers 1 to 17 in a row so that each adjacent pair adds up to a square number?

A particular technique for solving Sudoku puzzles, known as "naked pair", is explained in this easy-to-read article.

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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?

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Use the clues about the shaded areas to help solve this sudoku

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Each of the main diagonals of this sudoku must contain the numbers 1 to 9 and each rectangle width the numbers 1 to 4.

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Two sudokus in one. Challenge yourself to make the necessary connections.

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Different combinations of the weights available allow you to make different totals. Which totals can you make?

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Each clue in this Sudoku is the product of the two numbers in adjacent cells.

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Find the values of the nine letters in the sum: FOOT + BALL = GAME

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How many solutions can you find to this sum? Each of the different letters stands for a different number.