# Resources tagged with: Addition & subtraction

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### Number Pyramids

##### Age 11 to 14Challenge Level

Try entering different sets of numbers in the number pyramids. How does the total at the top change?

### Have You Got It?

##### Age 11 to 14Challenge Level

Can you explain the strategy for winning this game with any target?

### Countdown

##### Age 7 to 14Challenge Level

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

### Countdown Fractions

##### Age 11 to 16Challenge Level

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

### Consecutive Negative Numbers

##### Age 11 to 14Challenge Level

Do you notice anything about the solutions when you add and/or subtract consecutive negative numbers?

### Got it for Two

##### Age 7 to 14Challenge Level

Got It game for an adult and child. How can you play so that you know you will always win?

### Making a Difference

##### Age 11 to 14Challenge Level

How many different differences can you make?

### Magic Squares for Special Occasions

##### Age 11 to 16

This article explains how to make your own magic square to mark a special occasion with the special date of your choice on the top line.

### Making Maths: Double-sided Magic Square

##### Age 7 to 14Challenge Level

Make your own double-sided magic square. But can you complete both sides once you've made the pieces?

##### Age 11 to 14Challenge 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?

### Number Daisy

##### Age 11 to 14Challenge 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?

### Weights

##### Age 11 to 14Challenge Level

Different combinations of the weights available allow you to make different totals. Which totals can you make?

### Magic Letters

##### Age 11 to 14Challenge Level

Charlie has made a Magic V. Can you use his example to make some more? And how about Magic Ls, Ns and Ws?

### Cinema Problem

##### Age 11 to 14Challenge Level

A cinema has 100 seats. Show how it is possible to sell exactly 100 tickets and take exactly Â£100 if the prices are Â£10 for adults, 50p for pensioners and 10p for children.

### Card Trick 2

##### Age 11 to 14Challenge Level

Can you explain how this card trick works?

### Cunning Card Trick

##### Age 11 to 14Challenge Level

Delight your friends with this cunning trick! Can you explain how it works?

### Alphabetti Sudoku

##### Age 11 to 16Challenge Level

This Sudoku requires you to do some working backwards before working forwards.

### 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.

### Eleven

##### Age 11 to 14Challenge Level

Replace each letter with a digit to make this addition correct.

### Consecutive Numbers

##### Age 7 to 14Challenge Level

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

### Difference Sudoku

##### Age 14 to 16Challenge Level

Use the differences to find the solution to this Sudoku.

### Clocked

##### Age 11 to 14Challenge 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?

### Can You Make 100?

##### Age 11 to 14Challenge Level

How many ways can you find to put in operation signs (+ - x Ã·) to make 100?

### Crossed Ends

##### Age 11 to 14Challenge Level

Crosses can be drawn on number grids of various sizes. What do you notice when you add opposite ends?

### Pair Sums

##### Age 11 to 14Challenge Level

Five numbers added together in pairs produce: 0, 2, 4, 4, 6, 8, 9, 11, 13, 15 What are the five numbers?

### Cubes Within Cubes

##### Age 7 to 14Challenge 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?

### Nice or Nasty for Two

##### Age 7 to 14Challenge Level

Some Games That May Be Nice or Nasty for an adult and child. Use your knowledge of place value to beat your opponent.

### Cayley

##### Age 11 to 14Challenge Level

The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?

### Summing Consecutive Numbers

##### Age 11 to 14Challenge 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?

##### Age 11 to 14Challenge Level

By selecting digits for an addition grid, what targets can you make?

### Charitable Pennies

##### Age 7 to 14Challenge Level

Investigate the different ways that fifteen schools could have given money in a charity fundraiser.

### Nice or Nasty

##### Age 7 to 14Challenge Level

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

### Aba

##### Age 11 to 14Challenge Level

In the following sum the letters A, B, C, D, E and F stand for six distinct digits. Find all the ways of replacing the letters with digits so that the arithmetic is correct.

### Football Sum

##### Age 11 to 14Challenge Level

Find the values of the nine letters in the sum: FOOT + BALL = GAME

### Two and Two

##### Age 11 to 16Challenge Level

How many solutions can you find to this sum? Each of the different letters stands for a different number.

### Postage

##### Age 14 to 16Challenge 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. . . .

### Twenty20

##### Age 7 to 16Challenge Level

Fancy a game of cricket? Here is a mathematical version you can play indoors without breaking any windows.

### Pole Star Sudoku 2

##### Age 11 to 16Challenge Level

This Sudoku, based on differences. Using the one clue number can you find the solution?

### Diagonal Sums

##### Age 7 to 14Challenge 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?

### More Children and Plants

##### Age 7 to 14Challenge Level

This challenge extends the Plants investigation so now four or more children are involved.

##### Age 11 to 14Challenge Level

What happens when you add a three digit number to its reverse?

### Subtraction Surprise

##### Age 7 to 14Challenge Level

Try out some calculations. Are you surprised by the results?

### More Plant Spaces

##### Age 7 to 14Challenge 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.

### Consecutive Seven

##### Age 11 to 14Challenge 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?

##### Age 11 to 14Challenge Level

Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some. . . .

### Plants

##### Age 5 to 14Challenge Level

Three children are going to buy some plants for their birthdays. They will plant them within circular paths. How could they do this?

### Pairs

##### Age 11 to 14Challenge Level

Ann thought of 5 numbers and told Bob all the sums that could be made by adding the numbers in pairs. The list of sums is 6, 7, 8, 8, 9, 9, 10,10, 11, 12. Help Bob to find out which numbers Ann was. . . .

### Connect Three

##### Age 11 to 16Challenge Level

In this game the winner is the first to complete a row of three. Are some squares easier to land on than others?

### Score

##### Age 11 to 14Challenge Level

There are exactly 3 ways to add 4 odd numbers to get 10. Find all the ways of adding 8 odd numbers to get 20. To be sure of getting all the solutions you will need to be systematic. What about. . . .