You can very quickly enter a logical data series (such as 1, 2, 3 or Monday, Tuesday, Wednesday) in contiguous cells by using the Auto Fill feature. By default, Excel recognizes the days of the week, the months of the year, and any numeric series, including dates and times. You can easily create a custom fill series by adding the series to the Custom Lists page of the Excel Preferences dialog box.
To fill a series of cells with a series of data, you start by entering the first series element into the cell you want the series to start in. (The first element doesn’t have to be the first entry in a list; Excel will start the series with any entry, and repeat the series to fill the number of destination cells you select.) Then drag the cell’s fill handle down or to the right to increase the series, or up or to the left to decrease the series. If you want the series to fill backward (Friday, Thursday, Wednesday, and so on) enter the first two series items in the first two cells, select the two cells, and then drag the fill handle of the selection.
When you release the fill handle, the Auto Fill Options button appears. This is a smart button. Clicking the button displays a menu of options tailored specifically for the type of data series you’re filling.
These basic fill options always appear on the Auto Fill Options menu:
Copy Cells. By selecting this option, you can copy the content of the source cell into the selected destination cells.
Fill Formatting Only. By selecting this option, you can copy the font and cell formatting of the source cell into the destination cells.
Fill Without Formatting. By selecting this option, you can copy the content of a single source cell or fill a series based on multiple source cells, while maintaining the original formatting of the destination cells.
If Excel recognizes the source cell or cells as belonging to any known series, the Auto Fill Options menu includes the Fill Series option. By selecting this option, you can fill the destination cells with a logical series based on the source cell or cells.
If the source cell content is a day of the week, the Auto Fill Options menu includes the Fill Days and Fill Weekdays options. If the source cell content is a date, the menu includes those two options as well as the Fill Months and Fill Years options.