Computers are mathematical machines that operate on digital information, meaning the information is either ‘off’ or ‘on’. This is represented in computing with the binary number system, which only uses 0 and 1. These binary digits are called bits in computing. 

So, in computing 0 = off and 1 = on. This allows computers to use a series of ‘switches’ to make decisions based on a series of logical decisions (this is what a computer programme or ‘code’ is).  

These pages explore and explain binary further: 
What is digital data? – BBC Bitesize 

Binary Number System ( 

Beyond Programming: Binary ( 

How computers see the world – Binary – KS3 Computer Science Revision – BBC Bitesize 


This could be explored from as early as First Level, MTH 1-12a states that learners should have ‘discussed the important part that numbers play in the world and explored a variety of systems that have been used by civilisations throughout history to record numbers.’  

CS Unplugged has 6 great activities to introduce the binary system to young learners. 


Everything on a computer is represented by binary, including images. Every image is created on a grid with each box on it called a pixel. Every pixel is either ‘off’ or ‘on’ and represented as 0 or 1. Once learners are confident with this concept you can even get them to calculate the size of larger binary pictures or coloured images – this involves multiples and conversion of units (every 8 bits is converted to a byte!) 

These are some fun unplugged activities to introduce learners to binary representation of images:
How do digital images work? – BBC Bitesize 

Colour by numbers – CS Unplugged 

Binary Images ( 


If you are working with more confident learners, you might want to explore this even further. When the computer uses binary to ‘make decisions’ it is using Boolean logic, which is a form of algebra. Boolean statements are either ‘false’ or ‘true’ – that is they either meet a parameter or value, or they do not. In computing this is represented by binary, so FALSE = 0 and TRUE = 1. 

Using Boolean logic in programming – Boolean logic – KS3 Computer Science Revision – BBC Bitesize 


Famous mathematicians involved in computing: 

The modern binary number system was developed by Gottfried Leibniz in the 17th century.
Boolean logic was developed by George Boole, a 19th century mathematician. 

Ada Lovelace invented the first computer programme in the 19th century. 

Alan Turing was a mathematician who used one of the first ever computers, called Colossus, to crack the German communications code during WWII, and helping the Allies end the war.

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