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A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.

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List any 3 numbers. It is always possible to find a subset of adjacent numbers that add up to a multiple of 3. Can you explain why and prove it?

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Can you explain the strategy for winning this game with any target?

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The triangle OMN has vertices on the axes with whole number co-ordinates. How many points with whole number coordinates are there on the hypotenuse MN?

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Is there a relationship between the coordinates of the endpoints of a line and the number of grid squares it crosses?

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Find some examples of pairs of numbers such that their sum is a factor of their product. eg. 4 + 12 = 16 and 4 × 12 = 48 and 16 is a factor of 48.

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Can you find a way to identify times tables after they have been shifted up or down?

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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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A and B are two interlocking cogwheels having p teeth and q teeth respectively. One tooth on B is painted red. Find the values of p and q for which the red tooth on B contacts every gap on the. . . .

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I added together the first 'n' positive integers and found that my answer was a 3 digit number in which all the digits were the same...

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

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Take any pair of two digit numbers x=ab and y=cd where, without loss of generality, ab > cd . Form two 4 digit numbers r=abcd and s=cdab and calculate: {r^2 - s^2} /{x^2 - y^2}.

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Is there an efficient way to work out how many factors a large number has?

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A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?

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Great Granddad is very proud of his telegram from the Queen congratulating him on his hundredth birthday and he has friends who are even older than he is... When was he born?

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Find some triples of whole numbers a, b and c such that a^2 + b^2 + c^2 is a multiple of 4. Is it necessarily the case that a, b and c must all be even? If so, can you explain why?

Can you find any perfect numbers? Read this article to find out more...

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Can you find a cuboid that has a surface area of exactly 100 square units. Is there more than one? Can you find them all?

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Which pairs of cogs let the coloured tooth touch every tooth on the other cog? Which pairs do not let this happen? Why?

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Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?

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Imagine we have four bags containing numbers from a sequence. What numbers can we make now?

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Got It game for an adult and child. How can you play so that you know you will always win?

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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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Caroline and James pick sets of five numbers. Charlie chooses three of them that add together to make a multiple of three. Can they stop him?

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

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Choose any 3 digits and make a 6 digit number by repeating the 3 digits in the same order (e.g. 594594). Explain why whatever digits you choose the number will always be divisible by 7, 11 and 13.

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An environment which simulates working with Cuisenaire rods.

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Explore the relationship between simple linear functions and their graphs.

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Follow this recipe for sieving numbers and see what interesting patterns emerge.

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Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.

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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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Factor track is not a race but a game of skill. The idea is to go round the track in as few moves as possible, keeping to the rules.

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Three people chose this as a favourite problem. It is the sort of problem that needs thinking time - but once the connection is made it gives access to many similar ideas.

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Explain why the arithmetic sequence 1, 14, 27, 40, ... contains many terms of the form 222...2 where only the digit 2 appears.

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Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?

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Here is a chance to create some Celtic knots and explore the mathematics behind them.

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How many integers between 1 and 1200 are NOT multiples of any of the numbers 2, 3 or 5?

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Think of any three-digit number. Repeat the digits. The 6-digit number that you end up with is divisible by 91. Is this a coincidence?

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A game in which players take it in turns to choose a number. Can you block your opponent?

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Each letter represents a different positive digit AHHAAH / JOKE = HA What are the values of each of the letters?

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Nine squares are fitted together to form a rectangle. Can you find its dimensions?

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Can you work out what step size to take to ensure you visit all the dots on the circle?

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You are given the Lowest Common Multiples of sets of digits. Find the digits and then solve the Sudoku.

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Take any prime number greater than 3 , square it and subtract one. Working on the building blocks will help you to explain what is special about your results.

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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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Can you work out what size grid you need to read our secret message?