When entering numbers into a spreadsheet, one often needs to ensure that the number format is consistent. For example, if the numbers represent prices, you may want to display the appropriate currency symbol or you may simply want to ensure that the number of decimals displayed is always the same.

Unless the user specifies otherwise, all numbers in Excel are rendered in the "General" format. What this means is that numbers are displayed exactly as one enters them: if you enter two decimals, two decimals are displayed; if you went to one decimal, one decimal is displayed; and so forth.

To specify the number format, the best idea is usually to select the entire column. To do this, simply click on the letter or letters representing the column. (If text is contained in the selection, it will not be affected by the number format you specify.)

Number formats are found in the "Numbers" section of the Home Tab of the Excel Ribbon. There are three principal formats related to numbers: the first is "Number", the second "Currency" and the third "Accounting". To access the full range of number formats, choose "More Number Formats" from the "Numbers" drop-down menu. Another method of accessing the same dialog box is to click on the launch button in the "Numbers" group of the Home Tab.

Clicking on any of the number formats on the left, displays a series of choices which enable you to refine the way that the format will work. For example, if you have numbers referring to an hourly rate, you might click the "Number" category in the left column and then specify two decimal places. The option which reads "Use Thousands Separator" is used to insert the appropriate separator to demarcate thousands. The separator used will depend on your locality: for example, in most European countries a dot will be used; in the UK or USA, a comma will be used.

The final option in the "Number" category controls the display of negative numbers. The default is to display a minus sign in front of the number and leave the colour of the number unchanged. However, you can also dispense with the minus sign and change the colour of negative numbers to red; or you can both change the colour of negative numbers to red and display the minus sign.

When we click the "Currency" category, we have pretty much the same choices with the addition of the currency symbol. We can specify which currency symbol is used or we can dispense with the symbol altogether.

The "Accounting" category is almost identical to "Currency". Once again, we can choose the currency symbol. However, you will notice that there are no choices relating to negative numbers. The convention in accountancy is to put negative numbers in brackets.

As an alternative to using the number dialog box, you can also click on one of the series of handy buttons which are used to apply each of the number formats with single click. There are also two buttons for decreasing and increasing the number of decimals displayed in the highlighted cells.

Finally, there may be times where, although you enter a number into a cell, you do not want Excel to treat it as a number. For example, if you have a column of data containing a client ID, although the ID may be numeric, you may not want Excel to treat it like a number or to modify it in any way. You will probably want it to stay exactly the way it was entered. Whenever this is the case, it is best to format the number as "Text". The simplest way of doing this is to select the appropriate column and in the number dialog box choose "Text" as the format.