There are 2 ways to format data in Excel and both yield different results.The first way is to use format cells. In the format cell dialog box, there is a tab called number. Using the tab, you can format data in different format, from general to number to dates. This is because excel store data only in 2 forms only, as values and as text. So the data in a cell can be presented as a standard number, as percentage, as dates, etc. We are not going to explain the simple form of presenting the data as you would probably know how to do that if you know the basics of Excel. But there is one category in the format that could do wonders to the presentation and that is the custom category. Using the custom category, you can format the data any way you want it. For example, you can format data in the cell as a date by putting the format you desire in the box as shown below:
Notice that I have typed in "d mmm yyyy" and the number 123456 is converted to 3 Jan 2238. To find out how to present different format of the number in Excel, you can first select the format (e.g. go to date category) you want to see and then click on the custom category. The field just below the label "Type:" will show you that the format for the date is presented as "d mmm yyyy". After understanding how this work, you can create formats you desire. Note that this method works only when the data in the cell is a number and changing the format does not change the underlying number in the cell, i.e. it remains as a number.