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

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

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?

Using your knowledge of the properties of numbers, can you fill all the squares on the board?

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

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.

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.

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

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?"

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?

A collection of resources to support work on Factors and Multiples at Secondary level.

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...

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

Factors and Multiples game for an adult and child. How can you make sure you win this game?

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

Can you find a relationship between the number of dots on the circle and the number of steps that will ensure that all points are hit?

The number 12 = 2^2 × 3 has 6 factors. What is the smallest natural number with exactly 36 factors?

The number 8888...88M9999...99 is divisible by 7 and it starts with the digit 8 repeated 50 times and ends with the digit 9 repeated 50 times. What is the value of the digit M?

Find the highest power of 11 that will divide into 1000! exactly.

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

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...

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

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

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?

The flow chart requires two numbers, M and N. Select several values for M and try to establish what the flow chart does.

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?

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

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

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.

Can you make lines of Cuisenaire rods that differ by 1?

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?

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.

Can you find any two-digit numbers that satisfy all of these statements?

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

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

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

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

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

What is the smallest number of answers you need to reveal in order to work out the missing headers?

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

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

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

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

Can you work out how many lengths I swim each day?

Play this game and see if you can figure out the computer's chosen number.

Data is sent in chunks of two different sizes - a yellow chunk has 5 characters and a blue chunk has 9 characters. A data slot of size 31 cannot be exactly filled with a combination of yellow and. . . .

Lyndon chose this as one of his favourite problems. It is accessible but needs some careful analysis of what is included and what is not. A systematic approach is really helpful.

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.

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