On Friday the magic plant was only 2 centimetres tall. Every day it doubled its height. How tall was it on Monday?

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

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.

Annie and Ben are playing a game with a calculator. What was Annie's secret number?

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?

Skippy and Anna are locked in a room in a large castle. The key to that room, and all the other rooms, is a number. The numbers are locked away in a problem. Can you help them to get out?

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

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

Explore Alex's number plumber. What questions would you like to ask? Don't forget to keep visiting NRICH projects site for the latest developments and questions.

This article for teachers describes how modelling number properties involving multiplication using an array of objects not only allows children to represent their thinking with concrete materials,. . . .

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?

Can you fill in this table square? The numbers 2 -12 were used to generate it with just one number used twice.

Zumf makes spectacles for the residents of the planet Zargon, who have either 3 eyes or 4 eyes. How many lenses will Zumf need to make all the different orders for 9 families?

Find the product of the numbers on the routes from A to B. Which route has the smallest product? Which the largest?

Ahmed is making rods using different numbers of cubes. Which rod is twice the length of his first rod?

Using the statements, can you work out how many of each type of rabbit there are in these pens?

Can you work out how many flowers there will be on the Amazing Splitting Plant after it has been growing for six weeks?

Twizzle, a female giraffe, needs transporting to another zoo. Which route will give the fastest journey?

Use the information about Sally and her brother to find out how many children there are in the Brown family.

Can you complete this jigsaw of the multiplication square?

Claire thinks she has the most sports cards in her album. "I have 12 pages with 2 cards on each page", says Claire. Ross counts his cards. "No! I have 3 cards on each of my pages and there are. . . .

The Man is much smaller than us. Can you use the picture of him next to a mug to estimate his height and how much tea he drinks?

Shut the Box game for an adult and child. Can you turn over the cards which match the numbers on the dice?

Suppose we allow ourselves to use three numbers less than 10 and multiply them together. How many different products can you find? How do you know you've got them all?

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?

There were 22 legs creeping across the web. How many flies? How many spiders?

This problem is designed to help children to learn, and to use, the two and three times tables.

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

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

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

At the beginning of May Tom put his tomato plant outside. On the same day he sowed a bean in another pot. When will the two be the same height?

Can you work out the arrangement of the digits in the square so that the given products are correct? The numbers 1 - 9 may be used once and once only.

Use your logical reasoning to work out how many cows and how many sheep there are in each field.

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?

This number has 903 digits. What is the sum of all 903 digits?

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?

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

A game for 2 or more players with a pack of cards. Practise your skills of addition, subtraction, multiplication and division to hit the target score.

Throw the dice and decide whether to double or halve the number. Will you be the first to reach the target?

Go through the maze, collecting and losing your money as you go. Which route gives you the highest return? And the lowest?

A game for 2 people using a pack of cards Turn over 2 cards and try to make an odd number or a multiple of 3.

In this investigation, you are challenged to make mobile phone numbers which are easy to remember. What happens if you make a sequence adding 2 each time?

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

If the numbers 5, 7 and 4 go into this function machine, what numbers will come out?

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?