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

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

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.

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

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...

A game for 2 people using a pack of cards Turn over 2 cards and try to make an odd number or a multiple of 3.

Use the interactivity to create some steady rhythms. How could you create a rhythm which sounds the same forwards as it does backwards?

A game that tests your understanding of remainders.

Use the interactivities to complete these Venn diagrams.

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?

In this activity, the computer chooses a times table and shifts it. Can you work out the table and the shift each time?

Andrew decorated 20 biscuits to take to a party. He lined them up and put icing on every second biscuit and different decorations on other biscuits. How many biscuits weren't decorated?

Starting with the number 180, take away 9 again and again, joining up the dots as you go. Watch out - don't join all the dots!

Can you complete this jigsaw of the multiplication square?

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

Investigate the smallest number of moves it takes to turn these mats upside-down if you can only turn exactly three at a time.

Imagine a wheel with different markings painted on it at regular intervals. Can you predict the colour of the 18th mark? The 100th mark?

If you have only four weights, where could you place them in order to balance this equaliser?

Each light in this interactivity turns on according to a rule. What happens when you enter different numbers? Can you find the smallest number that lights up all four lights?

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.

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

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

Can you predict when you'll be clapping and when you'll be clicking if you start this rhythm? How about when a friend begins a new rhythm at the same time?

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

This package contains a collection of problems from the NRICH website that could be suitable for students who have a good understanding of Factors and Multiples and who feel ready to take on some. . . .

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

Work out Tom's number from the answers he gives his friend. He will only answer 'yes' or 'no'.

What do the numbers shaded in blue on this hundred square have in common? What do you notice about the pink numbers? How about the shaded numbers in the other squares?

Find the frequency distribution for ordinary English, and use it to help you crack the code.

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

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

A game for 2 or more people. Starting with 100, subratct a number from 1 to 9 from the total. You score for making an odd number, a number ending in 0 or a multiple of 6.

In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?

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?"

Some 4 digit numbers can be written as the product of a 3 digit number and a 2 digit number using the digits 1 to 9 each once and only once. The number 4396 can be written as just such a product. Can. . . .

Nearly all of us have made table patterns on hundred squares, that is 10 by 10 grids. This problem looks at the patterns on differently sized square grids.

Four of these clues are needed to find the chosen number on this grid and four are true but do nothing to help in finding the number. Can you sort out the clues and find the number?

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

Rectangles are considered different if they vary in size or have different locations. How many different rectangles can be drawn on a chessboard?

Four of these clues are needed to find the chosen number on this grid and four are true but do nothing to help in finding the number. Can you sort out the clues and find the number?

What is the lowest number which always leaves a remainder of 1 when divided by each of the numbers from 2 to 10?

I am thinking of three sets of numbers less than 101. Can you find all the numbers in each set from these clues?

Can you see how these factor-multiple chains work? Find the chain which contains the smallest possible numbers. How about the largest possible numbers?

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

Look at three 'next door neighbours' amongst the counting numbers. Add them together. What do you notice?

I am thinking of three sets of numbers less than 101. They are the red set, the green set and the blue set. Can you find all the numbers in the sets from these clues?

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

How can you use just one weighing to find out which box contains the lighter ten coins out of the ten boxes?

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

This article for teachers describes how number arrays can be a useful reprentation for many number concepts.