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!
Mr McGregor has a magic potting shed. Overnight, the number of plants in it doubles. He'd like to put the same number of plants in each of three gardens, planting one garden each day. Can he do it?
Can you make a cycle of pairs that add to make a square number using all the numbers in the box below, once and once only?
Investigate the smallest number of moves it takes to turn these mats upside-down if you can only turn exactly three at a time.
Start by putting one million (1 000 000) into the display of your calculator. Can you reduce this to 7 using just the 7 key and add, subtract, multiply, divide and equals as many times as you like?
Have a go at this well-known challenge. Can you swap the frogs and toads in as few slides and jumps as possible?
Here is a chance to play a version of the classic Countdown Game.
Choose a symbol to put into the number sentence.
Place the numbers 1 to 10 in the circles so that each number is the difference between the two numbers just below it.
If you have only four weights, where could you place them in order to balance this equaliser?
This was a problem for our birthday website. Can you use four of these pieces to form a square? How about making a square with all five pieces?
Can you see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?
Ahmed has some wooden planks to use for three sides of a rabbit run against the shed. What quadrilaterals would he be able to make with the planks of different lengths?
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?
Can you explain the strategy for winning this game with any target?
This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.
Can you make the green spot travel through the tube by moving the yellow spot? Could you draw a tube that both spots would follow?
First Connect Three game for an adult and child. Use the dice numbers and either addition or subtraction to get three numbers in a straight line.
There are nine teddies in Teddy Town - three red, three blue and three yellow. There are also nine houses, three of each colour. Can you put them on the map of Teddy Town according to the rules?
A tetromino is made up of four squares joined edge to edge. Can this tetromino, together with 15 copies of itself, be used to cover an eight by eight chessboard?
A game for 2 players that can be played online. Players take it in turns to select a word from the 9 words given. The aim is to select all the occurrences of the same letter.
Can you locate the lost giraffe? Input coordinates to help you search and find the giraffe in the fewest guesses.
An environment which simulates working with Cuisenaire rods.
Help the bee to build a stack of blocks far enough to save his friend trapped in the tower.
What are the coordinates of the coloured dots that mark out the tangram? Try changing the position of the origin. What happens to the coordinates now?
How have the numbers been placed in this Carroll diagram? Which labels would you put on each row and column?
Can you find all the different ways of lining up these Cuisenaire rods?
A game for 2 people that everybody knows. You can play with a friend or online. If you play correctly you never lose!
Use the interactivity to create some steady rhythms. How could you create a rhythm which sounds the same forwards as it does backwards?
This problem is based on a code using two different prime numbers less than 10. You'll need to multiply them together and shift the alphabet forwards by the result. Can you decipher the code?
Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.
Is it possible to place 2 counters on the 3 by 3 grid so that there is an even number of counters in every row and every column? How about if you have 3 counters or 4 counters or....?
You have 4 red and 5 blue counters. How many ways can they be placed on a 3 by 3 grid so that all the rows columns and diagonals have an even number of red counters?
A generic circular pegboard resource.
Use the interactivity to find all the different right-angled triangles you can make by just moving one corner of the starting triangle.
Find out what a "fault-free" rectangle is and try to make some of your own.
What shaped overlaps can you make with two circles which are the same size? What shapes are 'left over'? What shapes can you make when the circles are different sizes?
Imagine a wheel with different markings painted on it at regular intervals. Can you predict the colour of the 18th mark? The 100th mark?
Try entering different sets of numbers in the number pyramids. How does the total at the top change?
Can you complete this jigsaw of the multiplication square?
Draw some isosceles triangles with an area of $9$cm$^2$ and a vertex at (20,20). If all the vertices must have whole number coordinates, how many is it possible to draw?
Place the numbers from 1 to 9 in the squares below so that the difference between joined squares is odd. How many different ways can you do this?
Use the Cuisenaire rods environment to investigate ratio. Can you find pairs of rods in the ratio 3:2? How about 9:6?
Can you find all the different triangles on these peg boards, and find their angles?
Hover your mouse over the counters to see which ones will be removed. Click to remove them. The winner is the last one to remove a counter. How you can make sure you win?
Can you coach your rowing eight to win?
How good are you at estimating angles?
Can you put the numbers from 1 to 15 on the circles so that no consecutive numbers lie anywhere along a continuous straight line?
Imagine picking up a bow and some arrows and attempting to hit the target a few times. Can you work out the settings for the sight that give you the best chance of gaining a high score?
Choose 13 spots on the grid. Can you work out the scoring system? What is the maximum possible score?