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Resources tagged with Addition & subtraction similar to Three Primes:

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Broad Topics > Calculations and Numerical Methods > Addition & subtraction

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I'm Eight

Stage: 1, 2, 3 and 4 Challenge Level: Challenge Level:1

Find a great variety of ways of asking questions which make 8.

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Magic Squares for Special Occasions

Stage: 3 and 4

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.

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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?

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Eleven

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

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

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Numbered Cars

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

I was looking at the number plate of a car parked outside. Using my special code S208VBJ adds to 65. Can you crack my code and use it to find out what both of these number plates add up to?

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Always the Same

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

Arrange the numbers 1 to 16 into a 4 by 4 array. Choose a number. Cross out the numbers on the same row and column. Repeat this process. Add up you four numbers. Why do they always add up to 34?

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Sept03 Sept03 Sept03

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

This number has 903 digits. What is the sum of all 903 digits?

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Sheep Talk

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

In sheep talk the only letters used are B and A. A sequence of words is formed by following certain rules. What do you notice when you count the letters in each word?

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Rod Measures

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

Using 3 rods of integer lengths, none longer than 10 units and not using any rod more than once, you can measure all the lengths in whole units from 1 to 10 units. How many ways can you do this?

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Chameleons

Stage: 3 Challenge Level: Challenge Level:1

Whenever two chameleons of different colours meet they change colour to the third colour. Describe the shortest sequence of meetings in which all the chameleons change to green if you start with 12. . . .

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Tis Unique

Stage: 3 Challenge Level: Challenge Level:1

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.

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Aba

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

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.

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Oddly

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

Find the sum of all three-digit numbers each of whose digits is odd.

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Cows and Sheep

Stage: 2 Challenge Level: Challenge Level:1

Use your logical reasoning to work out how many cows and how many sheep there are in each field.

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An Introduction to Magic Squares

Stage: 1, 2, 3 and 4

Find out about Magic Squares in this article written for students. Why are they magic?!

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Pyramids

Stage: 3 Challenge Level: Challenge Level:1

What are the missing numbers in the pyramids?

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Six Numbered Cubes

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

This task combines spatial awareness with addition and multiplication.

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Top-heavy Pyramids

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

Use the numbers in the box below to make the base of a top-heavy pyramid whose top number is 200.

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Always, Sometimes or Never? Number

Stage: 2 Challenge Level: Challenge Level:1

Are these statements always true, sometimes true or never true?

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1, 2, 3 Magic Square

Stage: 2 Challenge Level: Challenge Level:1

Arrange three 1s, three 2s and three 3s in this square so that every row, column and diagonal adds to the same total.

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Cubes Within Cubes

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

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?

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Brothers and Sisters

Stage: 2 Challenge Level: Challenge Level:1

Cassandra, David and Lachlan are brothers and sisters. They range in age between 1 year and 14 years. Can you figure out their exact ages from the clues?

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Dividing a Cake

Stage: 2 Challenge Level: Challenge Level:1

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?

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The Deca Tree

Stage: 2 Challenge Level: Challenge Level:1

Find out what a Deca Tree is and then work out how many leaves there will be after the woodcutter has cut off a trunk, a branch, a twig and a leaf.

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The Clockmaker's Birthday Cake

Stage: 2 Challenge Level: Challenge Level:1

The clockmaker's wife cut up his birthday cake to look like a clock face. Can you work out who received each piece?

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Journeys

Stage: 2 Challenge Level: Challenge Level:1

Investigate the different distances of these car journeys and find out how long they take.

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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?

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Arrange the Digits

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

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?

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Sometimes We Lose Things

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

Well now, what would happen if we lost all the nines in our number system? Have a go at writing the numbers out in this way and have a look at the multiplications table.

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Magic Triangle

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

Place the digits 1 to 9 into the circles so that each side of the triangle adds to the same total.

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Reverse Trick

Stage: 2 Challenge Level: Challenge Level:1

Tell your friends that you have a strange calculator that turns numbers backwards. What secret number do you have to enter to make 141 414 turn around?

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Six Ten Total

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

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

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Magic Squares 4x4

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

Fill in the numbers to make the sum of each row, column and diagonal equal to 34. For an extra challenge try the huge American Flag magic square.

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Number Juggle

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

Fill in the missing numbers so that adding each pair of corner numbers gives you the number between them (in the box).

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Clever Keys

Stage: 2 Short Challenge Level: Challenge Level:1

On a calculator, make 15 by using only the 2 key and any of the four operations keys. How many ways can you find to do it?

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Magic Circles

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

Put the numbers 1, 2, 3, 4, 5, 6 into the squares so that the numbers on each circle add up to the same amount. Can you find the rule for giving another set of six numbers?

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Two Number Lines

Stage: 2 Challenge Level: Challenge Level:1

Max and Mandy put their number lines together to make a graph. How far had each of them moved along and up from 0 to get the counter to the place marked?

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Buckets of Thinking

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

There are three buckets each of which holds a maximum of 5 litres. Use the clues to work out how much liquid there is in each bucket.

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Calendar Calculations

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

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?

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Consecutive Negative Numbers

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

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

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Oranges and Lemons

Stage: 2 Challenge Level: Challenge Level:1

On the table there is a pile of oranges and lemons that weighs exactly one kilogram. Using the information, can you work out how many lemons there are?

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Rocco's Race

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

Rocco ran in a 200 m race for his class. Use the information to find out how many runners there were in the race and what Rocco's finishing position was.

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Amy's Dominoes

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

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?

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Four Goodness Sake

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

Use 4 four times with simple operations so that you get the answer 12. Can you make 15, 16 and 17 too?

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Throw a 100

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

Can you score 100 by throwing rings on this board? Is there more than way to do it?

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Next Number

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

Find the next number in this pattern: 3, 7, 19, 55 ...

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Totality

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

This is an adding game for two players.

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Street Sequences

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

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

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Penta Post

Stage: 2 Challenge Level: Challenge Level:1

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?

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It Was 2010!

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

If the answer's 2010, what could the question be?