These sixteen children are standing in four lines of four, one behind the other. They are each holding a card with a number on it. Can you work out the missing numbers?

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?

Peter, Melanie, Amil and Jack received a total of 38 chocolate eggs. Use the information to work out how many eggs each person had.

Using some or all of the operations of addition, subtraction, multiplication and division and using the digits 3, 3, 8 and 8 each once and only once make an expression equal to 24.

Can you each work out the number on your card? What do you notice? How could you sort the cards?

Here is a picnic that Petros and Michael are going to share equally. Can you tell us what each of them will have?

There are three buckets each of which holds a maximum of 5 litres. Use the clues to work out how much liquid there is in each bucket.

Grandma found her pie balanced on the scale with two weights and a quarter of a pie. So how heavy was each pie?

Use the information to work out how many gifts there are in each pile.

Can you see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?

The value of the circle changes in each of the following problems. Can you discover its value in each problem?

48 is called an abundant number because it is less than the sum of its factors (without itself). Can you find some more abundant numbers?

The triangles in these sets are similar - can you work out the lengths of the sides which have question marks?

What happens when you add the digits of a number then multiply the result by 2 and you keep doing this? You could try for different numbers and different rules.

Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?

Imagine a pyramid which is built in square layers of small cubes. If we number the cubes from the top, starting with 1, can you picture which cubes are directly below this first cube?

Explore Alex's number plumber. What questions would you like to ask? What do you think is happening to the numbers?

After training hard, these two children have improved their results. Can you work out the length or height of their first jumps?

Here are the prices for 1st and 2nd class mail within the UK. You have an unlimited number of each of these stamps. Which stamps would you need to post a parcel weighing 825g?

The Scot, John Napier, invented these strips about 400 years ago to help calculate multiplication and division. Can you work out how to use Napier's bones to find the answer to these multiplications?

Can you complete this jigsaw of the multiplication square?

This article for teachers looks at how teachers can use problems from the NRICH site to help them teach division.

What is the lowest number which always leaves a remainder of 1 when divided by each of the numbers from 2 to 10?

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?

Benâ€™s class were cutting up number tracks. First they cut them into twos and added up the numbers on each piece. What patterns could they see?

Resources to support understanding of multiplication and division through playing with number.

Use your logical-thinking skills to deduce how much Dan's crisps and ice-cream cost altogether.

Can you see how these factor-multiple chains work? Find the chain which contains the smallest possible numbers. How about the largest possible numbers?

How will you decide which way of flipping over and/or turning the grid will give you the highest total?

This problem is based on the story of the Pied Piper of Hamelin. Investigate the different numbers of people and rats there could have been if you know how many legs there are altogether!

This challenge combines addition, multiplication, perseverance and even proof.

Work out Tom's number from the answers he gives his friend. He will only answer 'yes' or 'no'.

On my calculator I divided one whole number by another whole number and got the answer 3.125. If the numbers are both under 50, what are they?

Find at least one way to put in some operation signs (+ - x ÷) to make these digits come to 100.

This task combines spatial awareness with addition and multiplication.

Chandrika was practising a long distance run. Can you work out how long the race was from the information?

Use this information to work out whether the front or back wheel of this bicycle gets more wear and tear.

Look on the back of any modern book and you will find an ISBN code. Take this code and calculate this sum in the way shown. Can you see what the answers always have in common?

There are four equal weights on one side of the scale and an apple on the other side. What can you say that is true about the apple and the weights from the picture?

In November, Liz was interviewed for an article on a parents' website about learning times tables. Read the article here.

Four Go game for an adult and child. Will you be the first to have four numbers in a row on the number line?

Can you arrange 5 different digits (from 0 - 9) in the cross in the way described?

Put operations signs between the numbers 3 4 5 6 to make the highest possible number and lowest possible number.

A game for 2 people. Use your skills of addition, subtraction, multiplication and division to blast the asteroids.

Can you design a new shape for the twenty-eight squares and arrange the numbers in a logical way? What patterns do you notice?

During the third hour after midnight the hands on a clock point in the same direction (so one hand is over the top of the other). At what time, to the nearest second, does this happen?