This type of calculator has the least number of buttons and so the least number of functions.

In addition to the four basic operation keys (+, - , x, ), it will probably have a memory, square root (), percentage (%) and sign change (⁺/- ) function.

People who do not feel confident with maths often prefer to use a basic calculator. This may be because of its simple appearance. The other types of calculator can seem intimidating. However, a basic calculator can mean that you have to do a lot more maths yourself (eg making sure the order of operations are input correctly, inputting powers 'long-hand' and converting fractions to decimals before being able to input them, etc) A scientific calculator, for example, would do all these things for you.

The limited number of functions can limit the usefulness of this type of calculator, with two main exceptions:

A basic calculator can be very small and easy to carry in a purse or diary, and can be handy when you only need to perform basic operations, eg shopping on a budget or calculating discounts and offers.

A basic calculator can also be large (about A5 size) and have large keys. This is very useful if you use a calculator to add long lists of numbers particularly in financial services and accountancy. Some of these large key calculators can take paper till rolls (like the old adding machines) and some will show the last 10 numbers and signs input on a second display. This allows you to go back and check for input errors and correct them without having to re-add the entire list.

This is by far the most common type of calculator to use. A scientific calculator has a large number of functions (normally over 200) and is recommended at GCSE level maths. The functions include powers and roots (x^y and ^x ), logarithms (log), trigonometry (sin, cos and tan) and some statistics. It will also have a key.

Many scientific calculators now have fraction functions which allow you to input a fraction without having to convert it to a decimal first. It will also give answers as a fraction.

Some scientific calculators now show both the calculation input and the answer in the display area. This can help you check that your input is correct.

The large number of functions can make a scientific calculator look off putting. However, it is best to look at it in terms of whether it has the keys you need rather than the number of keys in total.

This is a special type of calculator and, as the name suggests, it enables you to draw and read graphs on its display. Graphical calculators have a very large number of functions (often more than 700) and are recommended for ‘A’ Level and University level maths. It can calculate advanced statistics, probability, complex numbers and financial functions. It will solve algebraic and differential equations and, of course, plot graphs in a number of styles.

It can take a long time to learn how to use a graphical calculator effectively. They are of value if you do need to use the type of advanced mathematical functions listed above. If you do, then it is worth taking the time to learn how to use a graphical calculator properly. If not, it would probably be better to stick to a scientific calculator.

There is a calculator facility in the Accessories of Windows 3.1, 95 and 98. This can be very convenient if you need to do a calculation whilst working through a document or project. It allows you to copy and paste numbers to and from your document.

If you click on View, the drop-down menu will allow you to choose whether you want to use a basic or scientific calculator. This option can be useful if you have a basic calculator but are finding that you occasionally need to use more functions that require a scientific calculator. The Help function is also useful on the scientific calculator as it tells you what each of the function keys does.

The advantages of this are that:

• you will have a choice of presentation styles
• you will be able to use formulae to perform calculations, including totalling the columns and rows
• column widths, row heights etc are set to deal with numbers rather than text
• you will be able to produce a large table on a spreadsheet but then include only the important extracts in the body of your project
• if you want to produce a diagram, chart or graph using IT, this table will serve as the starting point.

For help with the advantages and disadvantages of using IT to produce diagrams, charts and graphs, see the sub topics ‘Diagrams and Charts’ and ‘Graphs’ in the menu to the left of the screen.

For more help with IT and numbers see 'IT skills' in the menu to the left of the screen.