Ahmed is making rods using different numbers of cubes. Which rod is twice the length of his first rod?
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?
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?
There are 44 people coming to a dinner party. There are 15 square tables that seat 4 people. Find a way to seat the 44 people using all 15 tables, with no empty places.
Try adding together the dates of all the days in one week. Now multiply the first date by 7 and add 21. Can you explain what happens?
Choose a symbol to put into the number sentence.
If the answer's 2010, what could the question be?
Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?
Use the information about Sally and her brother to find out how many children there are in the Brown family.
Can you each work out the number on your card? What do you notice? How could you sort the cards?
Katie had a pack of 20 cards numbered from 1 to 20. She arranged the cards into 6 unequal piles where each pile added to the same total. What was the total and how could this be done?
This magic square has operations written in it, to make it into a maze. Start wherever you like, go through every cell and go out a total of 15!
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!
Can you see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?
This multiplication 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?
On Friday the magic plant was only 2 centimetres tall. Every day it doubled its height. How tall was it on Monday?
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.
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?
Using the statements, can you work out how many of each type of rabbit there are in these pens?
Number problems at primary level that require careful consideration.
This problem is designed to help children to learn, and to use, the two and three times tables.
In a Magic Square all the rows, columns and diagonals add to the 'Magic Constant'. How would you change the magic constant of this square?
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?
Can you work out some different ways to balance this equation?
This activity focuses on doubling multiples of five.
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?
Have a go at balancing this equation. Can you find different ways of doing it?
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?
Here is a picnic that Petros and Michael are going to share equally. Can you tell us what each of them will have?
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.
Use your logical-thinking skills to deduce how much Dan's crisps and ice-cream cost altogether.
What is the lowest number which always leaves a remainder of 1 when divided by each of the numbers from 2 to 10?
Four Go game for an adult and child. Will you be the first to have four numbers in a row on the number line?
This article for teachers looks at how teachers can use problems from the NRICH site to help them teach division.
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. . . .
What is happening at each box in these machines?
This task combines spatial awareness with addition and multiplication.
Can you arrange 5 different digits (from 0 - 9) in the cross in the way described?
Shut the Box game for an adult and child. Can you turn over the cards which match the numbers on the dice?
Use this grid to shade the numbers in the way described. Which numbers do you have left? Do you know what they are called?
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,. . . .
Can you see how these factor-multiple chains work? Find the chain which contains the smallest possible numbers. How about the largest possible numbers?
Put operations signs between the numbers 3 4 5 6 to make the highest possible number and lowest possible number.
Can you complete this jigsaw of the multiplication square?
Can you work out what a ziffle is on the planet Zargon?
Find the next number in this pattern: 3, 7, 19, 55 ...
What do you notice about the date 03.06.09? Or 08.01.09? This challenge invites you to investigate some interesting dates yourself.
Amy has a box containing domino pieces but she does not think it is a complete set. She has 24 dominoes in her box and there are 125 spots on them altogether. Which of her domino pieces are missing?
An old game but lots of arithmetic!
Look at what happens when you take a number, square it and subtract your answer. What kind of number do you get? Can you prove it?