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Broad Topics > Numbers and the Number System > Prime numbers

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Black Box

Stage: 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

This black box reveals random values of some important, but unusual, mathematical functions. Can you deduce the purpose of the black box?

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Various Venns

Stage: 2 Challenge Level: Challenge Level:1

Use the interactivities to complete these Venn diagrams.

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Factors and Multiples Game

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

A game in which players take it in turns to choose a number. Can you block your opponent?

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Factors and Multiples Puzzle

Stage: 3 Challenge Level: Challenge Level:1

A challenge that requires you to apply your knowledge of the properties of numbers. Can you fill all the squares on the board?

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Stars

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

Can you find a relationship between the number of dots on the circle and the number of steps that will ensure that all points are hit?

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Two Primes Make One Square

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

Can you make square numbers by adding two prime numbers together?

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Factor Lines

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

Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.

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Why 24?

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

Take any prime number greater than 3 , square it and subtract one. Working on the building blocks will help you to explain what is special about your results.

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Round and Round the Circle

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

What happens if you join every second point on this circle? How about every third point? Try with different steps and see if you can predict what will happen.

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Factors and Multiples Game for Two

Stage: 2 Challenge Level: Challenge Level:1

Factors and Multiples game for an adult and child. How can you make sure you win this game?

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Sieve of Eratosthenes

Stage: 3 Challenge Level: Challenge Level:1

Follow this recipe for sieving numbers and see what interesting patterns emerge.

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Weekly Challenge 44: Prime Counter

Stage: 5 Challenge Level: Challenge Level:1

A weekly challenge concerning prime numbers.

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Prime Sequences

Stage: 5 Challenge Level: Challenge Level:1

This group tasks allows you to search for arithmetic progressions in the prime numbers. How many of the challenges will you discover for yourself?

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Coins

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

A man has 5 coins in his pocket. Given the clues, can you work out what the coins are?

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Numbers as Shapes

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

Use cubes to continue making the numbers from 7 to 20. Are they sticks, rectangles or squares?

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An Introduction to Proof by Contradiction

Stage: 4 and 5

An introduction to proof by contradiction, a powerful method of mathematical proof.

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Different by One

Stage: 4 Challenge Level: Challenge Level:1

Make a line of green and a line of yellow rods so that the lines differ in length by one (a white rod)

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Bubble Trouble

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

Can you find just the right bubbles to hold your number?

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Factorial Fun

Stage: 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

How many divisors does factorial n (n!) have?

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A Conversation Piece

Stage: 2 Challenge Level: Challenge Level:1

Take the number 6 469 693 230 and divide it by the first ten prime numbers and you'll find the most beautiful, most magic of all numbers. What is it?

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Code Breaker

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

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?

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Penta Primes

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

Using all ten cards from 0 to 9, rearrange them to make five prime numbers. Can you find any other ways of doing it?

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Tom's Number

Stage: 2 Challenge Level: Challenge Level:1

Work out Tom's number from the answers he gives his friend. He will only answer 'yes' or 'no'.

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Strange Numbers

Stage: 3 Challenge Level: Challenge Level:1

All strange numbers are prime. Every one digit prime number is strange and a number of two or more digits is strange if and only if so are the two numbers obtained from it by omitting either. . . .

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What's Left?

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

Use this grid to shade the numbers in the way described. Which numbers do you have left? Do you know what they are called?

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Prompt Cards

Stage: 2 Challenge Level: Challenge Level:1

These two group activities use mathematical reasoning - one is numerical, one geometric.