One quarter of these coins are heads but when I turn over two coins, one third are heads. How many coins are there?

Katie and Will have some balloons. Will's balloon burst at exactly the same size as Katie's at the beginning of a puff. How many puffs had Will done before his balloon burst?

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

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

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.

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

56 406 is the product of two consecutive numbers. What are these two numbers?

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

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?

This big box multiplies anything that goes inside it by the same number. If you know the numbers that come out, what multiplication might be going on in the box?

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

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

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.

Number problems at primary level that may require resilience.

Find the words hidden inside each of the circles by counting around a certain number of spaces to find each letter in turn.

Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?

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

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

The discs for this game are kept in a flat square box with a square hole for each. Use the information to find out how many discs of each colour there are in the box.

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?

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...

Can you complete this jigsaw of the multiplication square?

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

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

You'll need to know your number properties to win a game of Statement Snap...

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.

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

How many different rectangles can you make using this set of rods?

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

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

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

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?

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?

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

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

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

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

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?"

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

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

Nine squares with side lengths 1, 4, 7, 8, 9, 10, 14, 15, and 18 cm can be fitted together to form a rectangle. What are the dimensions of the rectangle?

These red, yellow and blue spinners were each spun 45 times in total. Can you work out which numbers are on each spinner?

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.

Number problems at primary level to work on with others.

Guess the Dominoes for child and adult. Work out which domino your partner has chosen by asking good questions.

Suppose we allow ourselves to use three numbers less than 10 and multiply them together. How many different products can you find? How do you know you've got them all?

Investigate the sum of the numbers on the top and bottom faces of a line of three dice. What do you notice?

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

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?