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

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

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

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

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

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?

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?

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?

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

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

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