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Challenge level: Challenge Level:1 Challenge Level:2 Challenge Level:3

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Broad Topics > Applications > Codes and cryptography

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What Was in the Box?

Stage: 1 Challenge Level: Challenge Level:1

This big box adds something to any number that goes into it. If you know the numbers that come out, what addition might be going on in the box?

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Probably a Code?

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

Is the regularity shown in this encoded message noise or structure?

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Substitution Cipher

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

Find the frequency distribution for ordinary English, and use it to help you crack the code.

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Cracking Codes

Stage: 1 and 2

Jenny Murray describes how she developed her interest in making and breaking codes.

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James's Code Challenge

Stage: 2, 3, 4 and 5 Challenge Level: Challenge Level:1

The Enigma Project's James Grime has created a video code challenge. Watch it here!

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Building up to Coding

Stage: 1 and 2

This article describes the underlying mathematical ideas and skills involved in the important mathematical application of coding.

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Keeping it Safe and Quiet

Stage: 2, 3, 4 and 5

Simon Singh describes PKC, its origins, and why the science of code making and breaking is such a secret occupation.

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Some Secret Codes

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

Can you follow the rule to decode the messages?

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Unlocking the Case

Stage: 2 Challenge Level: Challenge Level:1

A case is found with a combination lock. There is one clue about the number needed to open the case. Can you find the number and open the case?

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Cipher Challenge Toolkit

Stage: 3, 4 and 5 Challenge Level: Challenge Level:1

Our toolkit removes the drudgery of codebreaking while leaving you to do the hard thinking!

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What's in a Name?

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

Here's a very elementary code that requires young children to read a table, and look for similarities and differences.

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Substitution Transposed

Stage: 3 and 4 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Substitution and Transposition all in one! How fiendish can these codes get?

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Transposition Cipher

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

Can you work out what size grid you need to read our secret message?

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Secondary Cipher Challenge Part 1

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

Here is the start of a six-part challenge. Can you get to the end and crack the final message?

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What's Happening?

Stage: 1 Challenge Level: Challenge Level:1

Shapes are added to other shapes. Can you see what is happening? What is the rule?

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Ip?

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

Seventh challenge cipher

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Jluuis or Even Asutguus?

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

Sixth challenge cipher

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Up a Semitone?

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

Fifth challenge cipher

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Semicircle

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

Fourth challenge cipher

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Vital?

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

Third challenge cipher

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A Fine Thing?

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

Second challenge cipher

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A Roman Conversion?

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

First cipher

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Secret Transmissions

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

How can Agent X transmit data on a faulty line and be sure that her message will get through?

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More Secret Transmissions

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

In 'Secret Transmissions', Agent X could send four-digit codes error free. Can you devise an error-correcting system for codes with more than four digits?

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Stage 5 Cipher Challenge

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

Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?

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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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The Best Card Trick?

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

Time for a little mathemagic! Choose any five cards from a pack and show four of them to your partner. How can they work out the fifth?