There are 73 NRICH Mathematical resources connected to Addition & subtraction, you may find related items under Calculations and Numerical Methods.
Broad Topics > Calculations and Numerical Methods > Addition & subtraction
Can You Make 100?
Age 11 to 14
Challenge Level
How many ways can you find to put in operation signs (+ - x ÷) to make 100?
Subtraction Surprise
Age 7 to 14
Challenge Level
Try out some calculations. Are you surprised by the results?
Making Sense of Positives and Negatives
Age 11 to 14
This article suggests some ways of making sense of calculations involving positive and negative numbers.
Nice or Nasty
Age 7 to 14
Challenge Level
There are nasty versions of this dice game but we'll start with the nice ones...
Countdown Fractions
Age 11 to 16
Challenge Level
Here is a chance to play a fractions version of the classic Countdown Game.
Countdown
Age 7 to 14
Challenge Level
Here is a chance to play a version of the classic Countdown Game.
Crossed Ends
Age 11 to 14
Challenge Level
Crosses can be drawn on number grids of various sizes. What do you notice when you add opposite ends?
Weights
Age 11 to 14
Challenge Level
Different combinations of the weights available allow you to make different totals. Which totals can you make?
Adding and Subtracting Positive and Negative Numbers
Age 11 to 14
How can we help students make sense of addition and subtraction of negative numbers?
Consecutive Negative Numbers
Age 11 to 14
Challenge Level
Do you notice anything about the solutions when you add and/or subtract consecutive negative numbers?
Connect Three
Age 11 to 16
Challenge Level
In this game the winner is the first to complete a row of three. Are some squares easier to land on than others?
Difference Sudoku
Age 14 to 16
Challenge Level
Use the differences to find the solution to this Sudoku.
Cunning Card Trick
Age 11 to 14
Challenge Level
Delight your friends with this cunning trick! Can you explain how it works?
Diagonal Sums
Age 7 to 14
Challenge Level
In this 100 square, look at the green square which contains the numbers 2, 3, 12 and 13. What is the sum of the numbers that are diagonally opposite each other? What do you notice?
Consecutive Seven
Age 11 to 14
Challenge Level
Can you arrange these numbers into 7 subsets, each of three numbers, so that when the numbers in each are added together, they make seven consecutive numbers?
Number Pyramids
Age 11 to 14
Challenge Level
Try entering different sets of numbers in the number pyramids. How does the total at the top change?
Cinema Problem
Age 11 to 14
Challenge Level
A cinema has 100 seats. Show how it is possible to sell exactly 100 tickets and take exactly £100 if the prices are £10 for adults, 50p for pensioners and 10p for children.
Cubes Within Cubes
Age 7 to 14
Challenge Level
We start with one yellow cube and build around it to make a 3x3x3 cube with red cubes. Then we build around that red cube with blue cubes and so on. How many cubes of each colour have we used?
Number Daisy
Age 11 to 14
Challenge Level
Can you find six numbers to go in the Daisy from which you can make all the numbers from 1 to a number bigger than 25?
Two and Two
Age 11 to 16
Challenge Level
How many solutions can you find to this sum? Each of the different letters stands for a different number.
Summing Consecutive Numbers
Age 11 to 14
Challenge Level
15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?
Plants
Age 5 to 14
Challenge Level
Three children are going to buy some plants for their birthdays. They will plant them within circular paths. How could they do this?
Consecutive Numbers
Age 7 to 14
Challenge Level
An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.
Charitable Pennies
Age 7 to 14
Challenge Level
Investigate the different ways that fifteen schools could have given money in a charity fundraiser.
Forwards Add Backwards
Age 11 to 14
Challenge Level
What happens when you add a three digit number to its reverse?
Add to 200
Age 11 to 14
Challenge Level
By selecting digits for an addition grid, what targets can you make?
Got it for Two
Age 7 to 14
Challenge Level
Got It game for an adult and child. How can you play so that you know you will always win?
Nice or Nasty for Two
Age 7 to 14
Challenge Level
Some Games That May Be Nice or Nasty for an adult and child. Use your knowledge of place value to beat your opponent.
Up, Down, Flying Around
Age 11 to 14
Challenge Level
Play this game to learn about adding and subtracting positive and negative numbers
Magic Letters
Age 11 to 14
Challenge Level
Charlie has made a Magic V. Can you use his example to make some more? And how about Magic Ls, Ns and Ws?
More Plant Spaces
Age 7 to 14
Challenge Level
This challenging activity involves finding different ways to distribute fifteen items among four sets, when the sets must include three, four, five and six items.
More Children and Plants
Age 7 to 14
Challenge Level
This challenge extends the Plants investigation so now four or more children are involved.
Twenty20
Age 7 to 16
Challenge Level
Fancy a game of cricket? Here is a mathematical version you can play indoors without breaking any windows.
Escape from the Castle
Age 7 to 14
Challenge Level
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?
2010: A Year of Investigations
Age 5 to 14
This article for teachers suggests ideas for activities built around 10 and 2010.
Pole Star Sudoku 2
Age 11 to 16
Challenge Level
This Sudoku, based on differences. Using the one clue number can you find the solution?
Alphabetti Sudoku
Age 11 to 16
Challenge Level
This Sudoku requires you to do some working backwards before working forwards.
Constellation Sudoku
Age 14 to 18
Challenge Level
Special clue numbers related to the difference between numbers in two adjacent cells and values of the stars in the "constellation" make this a doubly interesting problem.
Making Maths: Double-sided Magic Square
Age 7 to 14
Challenge Level
Make your own double-sided magic square. But can you complete both sides once you've made the pieces?
Multiply the Addition Square
Age 11 to 14
Challenge Level
If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?
An Introduction to Magic Squares
Age 7 to 16
Find out about Magic Squares in this article written for students. Why are they magic?!
Got it Article
Age 7 to 14
This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.
Clocked
Age 11 to 14
Challenge Level
Is it possible to rearrange the numbers 1,2......12 around a clock face in such a way that every two numbers in adjacent positions differ by any of 3, 4 or 5 hours?
Jugs of Wine
Age 11 to 14
Challenge Level
You have four jugs of 9, 7, 4 and 2 litres capacity. The 9 litre jug is full of wine, the others are empty. Can you divide the wine into three equal quantities?
Arrange the Digits
Age 11 to 14
Challenge Level
Can you arrange the digits 1,2,3,4,5,6,7,8,9 into three 3-digit numbers such that their total is close to 1500?
Postage
Age 14 to 16
Challenge Level
The country Sixtania prints postage stamps with only three values 6 lucres, 10 lucres and 15 lucres (where the currency is in lucres).Which values cannot be made up with combinations of these postage. . . .
NRICH is part of the family of activities in the Millennium Mathematics Project.