Codes and Codebreaking
What's in a Name?
Here's a very elementary code that requires young children to read a table, and look for similarities and differences.
What's Happening?
Shapes are added to other shapes. Can you see what is happening? What is the rule?
What Was in the Box?
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?
Cracking Codes
Jenny Murray describes how she developed her interest in making and breaking codes.
It's a Scrabble
Letters have different values in Scrabble - how are they decided upon? And would the values be the same for other languages?
Unlocking the Case
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?
Make 24
A card game for 2 or 4 players that will test your speedy arithmetic skills!
Substitution Cipher
Find the frequency distribution for ordinary English, and use it to help you crack the code.
Transposition Cipher
Can you work out what size grid you need to read our secret message?
Substitution Transposed
Substitution and Transposition all in one! How fiendish can these codes get?
The Best Card Trick?
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?
Secondary Cipher Challenge Part 1
Here is the start of a six-part challenge. Can you get to the end and crack the final message?
Secret Transmissions
How can Agent X transmit data on a faulty line and be sure that her message will get through?
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.
More Secret Transmissions
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?
Probably a Code?
Is the regularity shown in this encoded message noise or structure?
Stage 5 Cipher Challenge
Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?