In maths we call this 'MOD 26', instead of writing 26, we go back to 0.

However, you do have to be careful when you get to the end of the alphabet, because there is no letter number 26, so you have to go back to number 0. Then encoding, shifting the alphabet forward three places, is the same as adding three to your starting number: Aįor example, encoding the letter 'A' is 0+3=3, which is a 'D'.

So where's the maths? The maths comes if you think of the letters as numbers from 0 to 25 with A being 0, B being 1, C being 2 etc. This all seems very clever, but so far it's all been letters and no numbers. Have a go at trying to work out these messages which could have been sent by Caesar or his generals: When Caesar's generals came to decipher the messages, they knew that all they had to do was go back three places in the alphabet. When he got to the end of the alphabet, however, he would have to go right back to the beginning, so instead of an 'X', he would write an 'A', instead of a 'Y', he'd write a 'B' and instead of 'Z', he'd write a 'C'.Ĭomplete the table to find out how Caesar would encode the following message: Caesar's message Instead of a 'B', he would write an 'E', instead of a 'C', he would write an 'F' and so on. Instead of writing the letter 'A', he would write the letter thatĬomes three places further on in the alphabet, the letter 'D'. So Caesar would write messages to his generals in code. He needed a way of communicating his battle plans and tactics to everyone on his side without the enemy finding out.

Nearly 2000 years ago, Julius Caesar was busy taking over the world, invading countries to increase the size of the Roman Empire. In fact, some of the most famous code breakers in history have been mathematicians who have been able to use quite simple maths to uncovered plots, identify traitors and influence battles. But you should.Ĭracking codes and unravelling the true meaning of secret messages involves loads of maths, from simple addition and subtraction, to data handling and logical thinking. You probably wouldn't think of mathematics. When you think of spies and secret agents, you might think of lots of things nifty gadgets, foreign travel, dangerous missiles, fast cars and being shaken but not stirred.

6urj code to crack