Place the 16 different combinations of cup/saucer in this 4 by 4 arrangement so that no row or column contains more than one cup or saucer of the same colour.
A few extra challenges set by some young NRICH members.
Four friends must cross a bridge. How can they all cross it in just 17 minutes?
A challenging activity focusing on finding all possible ways of stacking rods.
A game for 2 people. Take turns placing a counter on the star. You win when you have completed a line of 3 in your colour.
A man has 5 coins in his pocket. Given the clues, can you work out what the coins are?
Cut four triangles from a square as shown in the picture. How many different shapes can you make by fitting the four triangles back together?
The letters of the word ABACUS have been arranged in the shape of a triangle. How many different ways can you find to read the word ABACUS from this triangular pattern?
This tricky challenge asks you to find ways of going across rectangles, going through exactly ten squares.
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?
Rather than using the numbers 1-9, this sudoku uses the nine different letters used to make the words "Advent Calendar".
This challenge extends the Plants investigation so now four or more children are involved.
The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?
Place six toy ladybirds into the box so that there are two ladybirds in every column and every row.
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.
Can you arrange the digits 1, 1, 2, 2, 3 and 3 to make a Number Sandwich?
This challenging activity involves finding different ways to distribute fifteen items among four sets, when the sets must include three, four, five and six items.
Try out the lottery that is played in a far-away land. What is the chance of winning?
Find the smallest whole number which, when mutiplied by 7, gives a product consisting entirely of ones.
This cube has ink on each face which leaves marks on paper as it is rolled. Can you work out what is on each face and the route it has taken?
Countries from across the world competed in a sports tournament. Can you devise an efficient strategy to work out the order in which they finished?
Find the values of the nine letters in the sum: FOOT + BALL = GAME
Can you order pictures of the development of a frog from frogspawn and of a bean seed growing into a plant?
Can you use the information to find out which cards I have used?
Use the clues to find out who's who in the family, to fill in the family tree and to find out which of the family members are mathematicians and which are not.
You need to find the values of the stars before you can apply normal Sudoku rules.
Use the interactivity to find all the different right-angled triangles you can make by just moving one corner of the starting triangle.
Bellringers have a special way to write down the patterns they ring. Learn about these patterns and draw some of your own.
A cinema has 100 seats. Show how it is possible to sell exactly 100 tickets and take exactly £100 if the prices are £10 for adults, 50p for pensioners and 10p for children.
Arrange 9 red cubes, 9 blue cubes and 9 yellow cubes into a large 3 by 3 cube. No row or column of cubes must contain two cubes of the same colour.
Can you find all the different triangles on these peg boards, and find their angles?
How many different triangles can you make on a circular pegboard that has nine pegs?
An extra constraint means this Sudoku requires you to think in diagonals as well as horizontal and vertical lines and boxes of nine.
Find out what a "fault-free" rectangle is and try to make some of your own.
There is a long tradition of creating mazes throughout history and across the world. This article gives details of mazes you can visit and those that you can tackle on paper.
Kate has eight multilink cubes. She has two red ones, two yellow, two green and two blue. She wants to fit them together to make a cube so that each colour shows on each face just once.
Can you find all the different ways of lining up these Cuisenaire rods?
Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?
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....?
Place the numbers 1 to 10 in the circles so that each number is the difference between the two numbers just below it.
Have a go at this well-known challenge. Can you swap the frogs and toads in as few slides and jumps as possible?
Can you find which shapes you need to put into the grid to make the totals at the end of each row and the bottom of each column?
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?
Can you put the numbers from 1 to 15 on the circles so that no consecutive numbers lie anywhere along a continuous straight line?
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?
Make your own double-sided magic square. But can you complete both sides once you've made the pieces?
Here are four cubes joined together. How many other arrangements of four cubes can you find? Can you draw them on dotty paper?
Each clue in this Sudoku is the product of the two numbers in adjacent cells.
Hover your mouse over the counters to see which ones will be removed. Click to remover them. The winner is the last one to remove a counter. How you can make sure you win?
You have been given nine weights, one of which is slightly heavier than the rest. Can you work out which weight is heavier in just two weighings of the balance?