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

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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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Here is a Sudoku with a difference! Use information about lowest common multiples to help you solve it.

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The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?

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

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

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

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

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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?

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

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

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

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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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Investigate the different ways that fifteen schools could have given money in a charity fundraiser.

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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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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?

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.

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Do you notice anything about the solutions when you add and/or subtract consecutive negative numbers?

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

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.

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An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

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

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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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I added together some of my neighbours' house numbers. Can you explain the patterns I noticed?

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Use the differences to find the solution to this Sudoku.

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

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

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Five numbers added together in pairs produce: 0, 2, 4, 4, 6, 8, 9, 11, 13, 15 What are the five numbers?

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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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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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15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?

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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?

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This task encourages you to investigate the number of edging pieces and panes in different sized windows.

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

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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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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!