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Explore the effect of reflecting in two intersecting mirror lines.

We asked what was the most interesting fact that you can find out about the number 2009. See the solutions that were submitted.
In this article, Jennifer Piggott talks about just a few of the problems with problems that make them such a rich source of mathematics and approaches to learning mathematics.
The very problem with problems, namely that they should result in you being stuck, is at the heart of what problem-solving is about. In this article for teachers I talk about just a few of the. . . .

Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some. . . .

A new problem posed by Lyndon Baker who has devised many NRICH problems over the years.

In how many ways can you give change for a ten pence piece?

My measurements have got all jumbled up! Swap them around and see if you can find a combination where every measurement is valid.

Imagine you are suspending a cube from one vertex (corner) and allowing it to hang freely. Now imagine you are lowering it into water until it is exactly half submerged. What shape does the surface. . . .
Read all about Pythagoras' mathematical discoveries in this article written for students.

Look carefully at the numbers. What do you notice? Can you make another square using the numbers 1 to 16, that displays the same properties?

The whole set of tiles is used to make a square. This has a green and blue border. There are no green or blue tiles anywhere in the square except on this border. How many tiles are there in the set?

This multiplication sum uses each of the digits 0 - 9 once and once only. Using the information given, can you replace the stars in the calculation with figures?

A ribbon runs around a box so that it makes a complete loop with two parallel pieces of ribbon on the top. How long will the ribbon be?

What is the largest cuboid you can wrap in an A3 sheet of paper?

The challenge is to find the values of the variables if you are to solve this Sudoku.

Can you find the area of a parallelogram defined by two vectors?

If a is the radius of the axle, b the radius of each ball-bearing, and c the radius of the hub, why does the number of ball bearings n determine the ratio c/a? Find a formula for c/a in terms of n.

If a ball is rolled into the corner of a room how far is its centre from the corner?

Two bags contain different numbers of red and blue balls. A ball is removed from one of the bags. The ball is blue. What is the probability that it was removed from bag A?

The number 3723(in base 10) is written as 123 in another base. What is that base?

Work with numbers big and small to estimate and calulate various quantities in biological contexts.

Work out the numerical values for these physical quantities.

When you change the units, do the numbers get bigger or smaller?

Choose the size of your pegboard and the shapes you can make. Can you work out the strategies needed to block your opponent?

Lolla bought a balloon at the circus. She gave the clown six coins to pay for it. What could Lolla have paid for the balloon?

How high will a ball taking a million seconds to fall travel?

What is the sum of: 6 + 66 + 666 + 6666 ............+ 666666666...6 where there are n sixes in the last term?

Use the clues about the symmetrical properties of these letters to place them on the grid.

What size square corners should be cut from a square piece of paper to make a box with the largest possible volume?

The shortest path between any two points on a snooker table is the straight line between them but what if the ball must bounce off one wall, or 2 walls, or 3 walls?

The interactive diagram has two labelled points, A and B. It is designed to be used with the problem "Cushion Ball"

A project, funded by the QCA and designed to develop case studies on implementing rich tasks that will be of use to teachers.
This reports on students’ responses to a mathematical problem from the NRICH website. In particular, we were interested in students’ responses to a question that provided an. . . .

This package contains a collection of problems from the NRICH website that could be suitable for students who have a good understanding of Factors and Multiples and who feel ready to take on some. . . .

Three teams have each played two matches. The table gives the total number points and goals scored for and against each team. Fill in the table and find the scores in the three matches.

In a league of 5 football teams which play in a round robin tournament show that it is possible for all five teams to be league leaders.

Find the values of the nine letters in the sum: FOOT + BALL = GAME

A maths-based Football World Cup simulation for teachers and students to use.

Using the picture of the fraction wall, can you find equivalent fractions?

Straight lines are drawn from each corner of a square to the mid points of the opposite sides. Express the area of the octagon that is formed at the centre as a fraction of the area of the square.

Generalise the sum of a GP by using derivatives to make the coefficients into powers of the natural numbers.

Ana and Ross looked in a trunk in the attic. They found old cloaks and gowns, hats and masks. How many possible costumes could they make?

A hallway floor is tiled and each tile is one foot square. Given that the number of tiles around the perimeter is EXACTLY half the total number of tiles, find the possible dimensions of the hallway.

Is it true that a large integer m can be taken such that: 1 + 1/2 + 1/3 + ... +1/m > 100 ?