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 see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?
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?
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.
Here is a chance to play a version of the classic Countdown Game.
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?
Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.
Try entering different sets of numbers in the number pyramids. How does the total at the top change?
Choose a symbol to put into the number sentence.
The number of plants in Mr McGregor's magic potting shed increases overnight. He'd like to put the same number of plants in each of his gardens, planting one garden each day. How can he do it?
Place the numbers 1 to 10 in the circles so that each number is the difference between the two numbers just below it.
The idea of this game is to add or subtract the two numbers on the dice and cover the result on the grid, trying to get a line of three. Are there some numbers that are good to aim for?
Can you explain the strategy for winning this game with any target?
Can you locate the lost giraffe? Input coordinates to help you search and find the giraffe in the fewest guesses.
A tilted square is a square with no horizontal sides. Can you devise a general instruction for the construction of a square when you are given just one of its sides?
This 100 square jigsaw is written in code. It starts with 1 and ends with 100. Can you build it up?
Choose 13 spots on the grid. Can you work out the scoring system? What is the maximum possible score?
Have a go at this well-known challenge. Can you swap the frogs and toads in as few slides and jumps as possible?
Semi-regular tessellations combine two or more different regular polygons to fill the plane. Can you find all the semi-regular tessellations?
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?
This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.
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!
Slide the pieces to move Khun Phaen past all the guards into the position on the right from which he can escape to freedom.
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.
A game for 2 players. Can be played online. One player has 1 red counter, the other has 4 blue. The red counter needs to reach the other side, and the blue needs to trap the red.
Try to stop your opponent from being able to split the piles of counters into unequal numbers. Can you find a strategy?
We can show that (x + 1)² = x² + 2x + 1 by considering the area of an (x + 1) by (x + 1) square. Show in a similar way that (x + 2)² = x² + 4x + 4
When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...
Triangular numbers can be represented by a triangular array of squares. What do you notice about the sum of identical triangle numbers?
An interactive activity for one to experiment with a tricky tessellation
How have the numbers been placed in this Carroll diagram? Which labels would you put on each row and column?
Find out what a "fault-free" rectangle is and try to make some of your own.
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 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. . . .
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?
A game for 2 people that everybody knows. You can play with a friend or online. If you play correctly you never lose!
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?
Can you make a right-angled triangle on this peg-board by joining up three points round the edge?
If you have only four weights, where could you place them in order to balance this equaliser?
Carry out some time trials and gather some data to help you decide on the best training regime for your rowing crew.
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?
Watch this film carefully. Can you find a general rule for explaining when the dot will be this same distance from the horizontal axis?
Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?
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?
Use the interactivities to fill in these Carroll diagrams. How do you know where to place the numbers?
Place six toy ladybirds into the box so that there are two ladybirds in every column and every row.
Here is a solitaire type environment for you to experiment with. Which targets can you reach?
Six balls of various colours are randomly shaken into a trianglular arrangement. What is the probability of having at least one red in the corner?
Use the blue spot to help you move the yellow spot from one star to the other. How are the trails of the blue and yellow spots related?
Meg and Mo need to hang their marbles so that they balance. Use the interactivity to experiment and find out what they need to do.