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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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A few extra challenges set by some young NRICH members.

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

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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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Bellringers have a special way to write down the patterns they ring. Learn about these patterns and draw some of your own.

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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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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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60 pieces and a challenge. What can you make and how many of the pieces can you use creating skeleton polyhedra?

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Use the differences to find the solution to this Sudoku.

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

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

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

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Make your own double-sided magic square. But can you complete both sides once you've made the pieces?

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

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This cube has ink on each face which leaves marks on paper as it is rolled. Can you work out what is on each face and the route it has taken?

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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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Have a go at this game which has been inspired by the Big Internet Math-Off 2019. Can you gain more columns of lily pads than your opponent?

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

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

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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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You have been given nine weights, one of which is slightly heavier than the rest. Can you work out which weight is heavier in just two weighings of the balance?

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

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

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

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

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Can you arrange the digits 1, 1, 2, 2, 3 and 3 to make a Number Sandwich?

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Solve the equations to identify the clue numbers in this Sudoku problem.

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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?

Find out about Magic Squares in this article written for students. Why are they magic?!

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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 numbers on an intersection that need to be placed in the surrounding cells. That is all you need to know to solve this sudoku.

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Countries from across the world competed in a sports tournament. Can you devise an efficient strategy to work out the order in which they finished?

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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 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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If you are given the mean, median and mode of five positive whole numbers, can you find the numbers?

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A man has 5 coins in his pocket. Given the clues, can you work out what the coins are?