Exploring Computer Hardware

Binary Numbers

Binary numbers only have ones and zeros, in other words you can only represent a number using a 1 and a 0. We do this using the binary or base 2 number system. Using this system we can count in binary. Here’s a table to help you:

With decimal numbers (or base 10), if you remember from primary school mathematics, reading from right to left you have your ones, tens, hundreds, thousands and so on. You get these by writing out your powers of 10.

100 = 1

101 = 10

102 = 100

103 = 1000

So to write the number 123, you’d have 3 ‘ones’, 2 ‘tens’, and 1 ‘hundred’. Adding these together you get 123.

With binary it’s the same principle, except ...