article
Cracking codes
Jenny Murray describes how she developed her interest in making and breaking codes.
problem
Favourite
What's happening?
Age
5 to 7
Challenge level
Shapes are added to other shapes. Can you see what is happening? What is the rule?
problem
Favourite
What was in the Box?
Age
5 to 7
Challenge level
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?
problem
Favourite
What's in a name?
Age
5 to 7
Challenge level
Here's a very elementary code that requires young children to read a table, and look for similarities and differences.
problem
It's a scrabble
Age
7 to 11
Challenge level
Letters have different values in Scrabble - how are they decided upon? And would the values be the same for other languages?
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Unlocking the case
Age
7 to 11
Challenge level
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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Some Secret Codes
Age
7 to 11
Challenge level
Can you follow the rule to decode the messages?
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The Best Card Trick?
Age
11 to 16
Challenge level
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?
problem
Favourite
Substitution Cipher
Age
11 to 14
Challenge level
Find the frequency distribution for ordinary English, and use it to help you crack the code.
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Secondary Cipher Challenge Part 1
Age
11 to 16
Challenge level
Here is the start of a six-part challenge. Can you get to the end and crack the final message?
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Transposition cipher
Age
11 to 16
Challenge level
Can you work out what size grid you need to read our secret message?
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Substitution Transposed
Age
11 to 16
Challenge level
Substitution and Transposition all in one! How fiendish can these codes get?
article
Keeping it safe and quiet
Simon Singh describes PKC, its origins, and why the science of code making and breaking is such a secret occupation.
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Secret Transmissions
Age
14 to 16
Challenge level
How can Agent X transmit data on a faulty line and be sure that her message will get through?
problem
Favourite
Probably a code?
Age
16 to 18
Challenge level
Is the regularity shown in this encoded message noise or structure?
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Stage 5 Cipher Challenge
Age
16 to 18
Challenge level
Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?
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More Secret Transmissions
Age
16 to 18
Challenge level
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?