2. Denary and Binary

The two number systems we will discuss in this section are denary and binary.

The 'base' of a number system describes how many symbols (agreed shapes) there are in that system. Therefore 'denary' has ten, and 'binary' has two.

There are others as well, for example 'Hexadecimal' which has sixteen symbols.

Base 10 number system (denary)

In our everyday lives we use a 'Denary' number system which has the number symbols 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.

This is called a 'base-10' number system, because there are ten symbols involved.

Here are some examples of denary numbers:

• 5
• 249
• 316
• 8715

Base 2 number system (binary)

You already know that computers need to use binary numbers to process data.

Binary is a 'base-2' type of number which has only two symbols, and these are chosen to be 1 or a 0

Here are some examples of binary numbers:

• 1
• 101
• 1101
• 11011001