Whole numbers (e.g. -2, -1, 0, 1, 2, 3....) can only be written in one way, however other numbers can be written in two different ways:

1) As a fraction e.g. the number half way between 2 and 3 is shown as 2½. Note that sometimes you will see two and a half written as 2 1/2 ('cos it's easier to do this on the computer).

2) Or as a decimal e.g. 2.5.

Examples of a few other decimals:

0.1 is the same as 1/10
0.01 is the same as 1/100
0.001 is the same as 1/1000
0.3333333... is the same as 1/3 (divide 1 by 3 on your calculator and you get a never ending string of "recurring" 3's after the decimal point).

Terminating Decimals
These are decimals which end straight away (1.5, 0.1234).

Non-Terminating Decimals
These are numbers which have decimals which do not stop. These include numbers such as Pi ( )or recurring decimals like a third (1/3 - which we saw above).

Decimal Places
Decimals may not be very short. Many answers you work out may give a long string of decimal places which don't seem to end. Questions in an exam may ask you to give answers to a specific degree of accuracy by writing answers to a number of significant figures or to a number of decimal places. The tutorial here tells you all about this.