# Resources tagged with: Addition & subtraction

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### Countdown Fractions

##### Age 11 to 16Challenge Level

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

### As Easy as 1,2,3

##### Age 11 to 14Challenge Level

When I type a sequence of letters my calculator gives the product of all the numbers in the corresponding memories. What numbers should I store so that when I type 'ONE' it returns 1, and when I type. . . .

##### Age 11 to 14Challenge Level

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

### 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?

### Nice or Nasty

##### Age 7 to 14Challenge Level

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

### 3388

##### Age 11 to 14Challenge Level

Using some or all of the operations of addition, subtraction, multiplication and division and using the digits 3, 3, 8 and 8 each once and only once make an expression equal to 24.

### 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?

### 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.

### Have You Got It?

##### Age 11 to 14Challenge Level

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

### Largest Number

##### Age 11 to 14Challenge Level

What is the largest number you can make using the three digits 2, 3 and 4 in any way you like, using any operations you like? You can only use each digit once.

### 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?

### 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.

### 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.

### Eleven

##### Age 11 to 14Challenge Level

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

##### 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?

### Totality

##### Age 5 to 11Challenge Level

This is an adding game for two players. Can you be the first to reach the target?

### 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"?

##### 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. . . .

### Countdown

##### Age 7 to 14Challenge Level

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

### Dividing a Cake

##### Age 7 to 11Challenge Level

Annie cut this numbered cake into 3 pieces with 3 cuts so that the numbers on each piece added to the same total. Where were the cuts and what fraction of the whole cake was each piece?

### Code Breaker

##### Age 7 to 11Challenge Level

This problem is based on a code using two different prime numbers less than 10. You'll need to multiply them together and shift the alphabet forwards by the result. Can you decipher the code?

### Magic Matrix

##### Age 7 to 11Challenge Level

Find out why these matrices are magic. Can you work out how they were made? Can you make your own Magic Matrix?

### 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.

### Tis Unique

##### Age 11 to 14Challenge Level

This addition sum uses all ten digits 0, 1, 2...9 exactly once. Find the sum and show that the one you give is the only possibility.

### Worms

##### Age 7 to 11Challenge Level

Place this "worm" on the 100 square and find the total of the four squares it covers. Keeping its head in the same place, what other totals can you make?

### 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?

### 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?

### 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.

### A Numbered Route

##### Age 7 to 11Challenge Level

Can you draw a continuous line through 16 numbers on this grid so that the total of the numbers you pass through is as high as possible?

### Being Resourceful - Primary Number

##### Age 5 to 11Challenge Level

Number problems at primary level that require careful consideration.

### 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?

### Sorting the Numbers

##### Age 5 to 11Challenge Level

Complete these two jigsaws then put one on top of the other. What happens when you add the 'touching' numbers? What happens when you change the position of the jigsaws?

### Consecutive Negative Numbers

##### Age 11 to 14Challenge Level

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

### Cunning Card Trick

##### Age 11 to 14Challenge Level

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

##### Age 11 to 14Challenge Level

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

### 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?

### Charitable Pennies

##### Age 7 to 14Challenge Level

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

### Place Value as a Building Block for Developing Fluency in the Calculation Process

##### Age 5 to 11

This article for primary teachers encourages exploration of two fundamental ideas, exchange and 'unitising', which will help children become more fluent when calculating.

### Napier's Bones

##### Age 7 to 11Challenge Level

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?

### Card Trick 2

##### Age 11 to 14Challenge Level

Can you explain how this card trick works?

### Subtraction Surprise

##### Age 7 to 14Challenge Level

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

### Making Pathways

##### Age 7 to 11Challenge Level

Can you find different ways of creating paths using these paving slabs?

### Strike it Out for Two

##### Age 5 to 11Challenge Level

Strike it Out game for an adult and child. Can you stop your partner from being able to go?

### Street Sequences

##### Age 5 to 11Challenge Level

Investigate what happens when you add house numbers along a street in different ways.

### Football Sum

##### Age 11 to 14Challenge Level

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

### The Patent Solution

##### Age 11 to 14Challenge Level

A combination mechanism for a safe comprises thirty-two tumblers numbered from one to thirty-two in such a way that the numbers in each wheel total 132... Could you open the safe?

### 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?

### Interactive Balance

##### Age 5 to 11Challenge Level

In this simulation of a balance, you can drag numbers and parts of number sentences on to the trays. Have a play!

### Arrange the Digits

##### Age 11 to 14Challenge 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?