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
This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.
Here is a chance to play a version of the classic Countdown Game.
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?
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?
Imagine a wheel with different markings painted on it at regular
intervals. Can you predict the colour of the 18th mark? The 100th
If you have only four weights, where could you place them in order
to balance this equaliser?
Investigate the smallest number of moves it takes to turn these
mats upside-down if you can only turn exactly three at a time.
An environment which simulates working with Cuisenaire rods.
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 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?
Can you complete this jigsaw of the multiplication square?
Use the interactivities to complete these Venn diagrams.
Try to stop your opponent from being able to split the piles of counters into unequal numbers. Can you find a strategy?
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....?
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!
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. . . .
Arrange the four number cards on the grid, according to the rules,
to make a diagonal, vertical or horizontal line.
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?
How have the numbers been placed in this Carroll diagram? Which
labels would you put on each row and column?
Can you see why 2 by 2 could be 5? Can you predict what 2 by 10
What can you say about the values of n that make $7^n + 3^n$ a multiple of 10? Are there other pairs of integers between 1 and 10 which have similar properties?
Use the interactivity to create some steady rhythms. How could you
create a rhythm which sounds the same forwards as it does
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?
Work out how to light up the single light. What's the rule?
In this activity, the computer chooses a times table and shifts it. Can you work out the table and the shift each time?
Try entering different sets of numbers in the number pyramids. How does the total at the top change?
Choose 13 spots on the grid. Can you work out the scoring system? What is the maximum possible score?
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?
Have a go at this well-known challenge. Can you swap the frogs and toads in as few slides and jumps as possible?
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?
These formulae are often quoted, but rarely proved. In this article, we derive the formulae for the volumes of a square-based pyramid and a cone, using relatively simple mathematical concepts.
You have 27 small cubes, 3 each of nine colours. Use the small
cubes to make a 3 by 3 by 3 cube so that each face of the bigger
cube contains one of every colour.
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?
Can you put the 25 coloured tiles into the 5 x 5 square so that no
column, no row and no diagonal line have tiles of the same colour
Choose a symbol to put into the number sentence.
Triangle numbers can be represented by a triangular array of
squares. What do you notice about the sum of identical triangle
Use the interactivity to investigate what kinds of triangles can be
drawn on peg boards with different numbers of pegs.
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?
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?
Practise your diamond mining skills and your x,y coordination in this homage to Pacman.
Can you coach your rowing eight to win?
NRICH December 2006 advent calendar - a new tangram for each day in
the run-up to Christmas.
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?
Investigate which numbers make these lights come on. What is the smallest number you can find that lights up all the lights?
Can you put the numbers 1 to 8 into the circles so that the four
calculations are correct?
A generic circular pegboard resource.
Try out the lottery that is played in a far-away land. What is the
chance of winning?
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?