Search by Topic

Filter by: Content type:
Stage:
Challenge level: Challenge Level:1 Challenge Level:2 Challenge Level:3

There are 254 results

Broad Topics > Calculations and Numerical Methods > Addition & subtraction

problem icon

Dicey Addition

Stage: 1 and 2 Challenge Level: Challenge Level:1

Who said that adding couldn't be fun?

problem icon

Six Numbered Cubes

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

This task combines spatial awareness with addition and multiplication.

problem icon

Six Ten Total

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

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

problem icon

Double or Halve?

Stage: 1 Challenge Level: Challenge Level:1

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

problem icon

Build it Up

Stage: 2 Challenge Level: Challenge Level:1

Can you find all the ways to get 15 at the top of this triangle of numbers?

problem icon

Five Steps to 50

Stage: 1 Challenge Level: Challenge Level:1

Use five steps to count forwards or backwards in 1s or 10s to get to 50. What strategies did you use?

problem icon

Unit Differences

Stage: 1 Challenge Level: Challenge Level:1

This challenge is about finding the difference between numbers which have the same tens digit.

problem icon

What Could it Be?

Stage: 1 Challenge Level: Challenge Level:1

In this calculation, the box represents a missing digit. What could the digit be? What would the solution be in each case?

problem icon

Play to 37

Stage: 2 Challenge Level: Challenge Level:1

In this game for two players, the idea is to take it in turns to choose 1, 3, 5 or 7. The winner is the first to make the total 37.

problem icon

Dice in a Corner

Stage: 2 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

How could you arrange at least two dice in a stack so that the total of the visible spots is 18?

problem icon

Exploring Number Patterns You Make

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

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

problem icon

Take Three Numbers

Stage: 2 Challenge Level: Challenge Level:1

What happens when you add three numbers together? Will your answer be odd or even? How do you know?

problem icon

What Was in the Box?

Stage: 1 Challenge Level: Challenge Level:1

This big box adds something to any number that goes into it. If you know the numbers that come out, what addition might be going on in the box?

problem icon

Fifteen Cards

Stage: 2 Challenge Level: Challenge Level:1

Can you use the information to find out which cards I have used?

problem icon

Dotty Six

Stage: 1 and 2 Challenge Level: Challenge Level:1

Dotty Six is a simple dice game that you can adapt in many ways.

problem icon

Journeys in Numberland

Stage: 2 Challenge Level: Challenge Level:1

Tom and Ben visited Numberland. Use the maps to work out the number of points each of their routes scores.

problem icon

The Add and Take-away Path

Stage: 1 Challenge Level: Challenge Level:1

Two children made up a game as they walked along the garden paths. Can you find out their scores? Can you find some paths of your own?

problem icon

Pairs of Numbers

Stage: 1 Challenge Level: Challenge Level:1

If you have ten counters numbered 1 to 10, how many can you put into pairs that add to 10? Which ones do you have to leave out? Why?

problem icon

Sitting Round the Party Tables

Stage: 1 and 2 Challenge Level: Challenge Level:1

Sweets are given out to party-goers in a particular way. Investigate the total number of sweets received by people sitting in different positions.

problem icon

Follow the Numbers

Stage: 2 Challenge Level: Challenge Level:1

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.

problem icon

Become Maths Detectives

Stage: 2 Challenge Level: Challenge Level:1

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.

problem icon

How Many?

Stage: 1 Challenge Level: Challenge Level:1

This project challenges you to work out the number of cubes hidden under a cloth. What questions would you like to ask?

problem icon

How Do You Do It?

Stage: 2 Challenge Level: Challenge Level:1

This group activity will encourage you to share calculation strategies and to think about which strategy might be the most efficient.

problem icon

Even and Odd

Stage: 1 Challenge Level: Challenge Level:1

This activity is best done with a whole class or in a large group. Can you match the cards? What happens when you add pairs of the numbers together?

problem icon

Sort Them Out (1)

Stage: 1 Challenge Level: Challenge Level:1

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

problem icon

Which Symbol?

Stage: 2 Challenge Level: Challenge Level:1

Choose a symbol to put into the number sentence.

problem icon

Nice or Nasty

Stage: 2 and 3 Challenge Level: Challenge Level:1

There are nasty versions of this dice game but we'll start with the nice ones...

problem icon

Strike it Out

Stage: 1 and 2 Challenge Level: Challenge Level:1

Use your addition and subtraction skills, combined with some strategic thinking, to beat your partner at this game.

problem icon

Countdown

Stage: 2 and 3 Challenge Level: Challenge Level:1

Here is a chance to play a version of the classic Countdown Game.

problem icon

Magic Vs

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

Can you put the numbers 1-5 in the V shape so that both 'arms' have the same total?

problem icon

Find the Difference

Stage: 1 Challenge Level: Challenge Level:2 Challenge Level:2

Place the numbers 1 to 6 in the circles so that each number is the difference between the two numbers just below it.

problem icon

Shut the Box

Stage: 1 Challenge Level: Challenge Level:1

An old game but lots of arithmetic!

problem icon

Oh! Harry!

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

A group of children are using measuring cylinders but they lose the labels. Can you help relabel them?

problem icon

How Much Did it Cost?

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

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

problem icon

Adding and Subtracting Positive and Negative Numbers

Stage: 2, 3 and 4

How can we help students make sense of addition and subtraction of negative numbers?

problem icon

Sea Level

Stage: 2 Challenge Level: Challenge Level:1

The picture shows a lighthouse and many underwater creatures. If you know the markings on the lighthouse are 1m apart, can you work out the distances between some of the different creatures?

problem icon

Tug Harder!

Stage: 2 Challenge Level: Challenge Level:1

In this game, you can add, subtract, multiply or divide the numbers on the dice. Which will you do so that you get to the end of the number line first?

problem icon

Tug of War

Stage: 1 Challenge Level: Challenge Level:1

Can you use the numbers on the dice to reach your end of the number line before your partner beats you?

problem icon

First Connect Three

Stage: 2 and 3 Challenge Level: Challenge Level:2 Challenge Level:2

The idea of this game is to add or subtract the two numbers on the dice and cover the result on the grid, trying to get a line of three. Are there some numbers that are good to aim for?

problem icon

Picture a Pyramid ...

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

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?

problem icon

Caterpillars

Stage: 1 Challenge Level: Challenge Level:2 Challenge Level:2

These caterpillars have 16 parts. What different shapes do they make if each part lies in the small squares of a 4 by 4 square?

problem icon

More Carroll Diagrams

Stage: 2 Challenge Level: Challenge Level:1

How have the numbers been placed in this Carroll diagram? Which labels would you put on each row and column?

problem icon

Carroll Diagrams

Stage: 1 Challenge Level: Challenge Level:2 Challenge Level:2

Use the interactivities to fill in these Carroll diagrams. How do you know where to place the numbers?

problem icon

Balance of Halves

Stage: 2 Challenge Level: Challenge Level:1

Investigate this balance which is marked in halves. If you had a weight on the left-hand 7, where could you hang two weights on the right to make it balance?

problem icon

Getting the Balance

Stage: 1 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

If you hang two weights on one side of this balance, in how many different ways can you hang three weights on the other side for it to be balanced?

problem icon

Number Lines

Stage: 1 Challenge Level: Challenge Level:1

Leah and Tom each have a number line. Can you work out where their counters will land? What are the secret jumps they make with their counters?

problem icon

Secret Number

Stage: 1 Challenge Level: Challenge Level:2 Challenge Level:2

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

problem icon

Making Longer, Making Shorter

Stage: 1 Challenge Level: Challenge Level:2 Challenge Level:2

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

problem icon

Domino Sorting

Stage: 1 Challenge Level: Challenge Level:1

Try grouping the dominoes in the ways described. Are there any left over each time? Can you explain why?

problem icon

Weighted Numbers

Stage: 1 Challenge Level: Challenge Level:1

Use the number weights to find different ways of balancing the equaliser.