Using the fill handle with formulas

The Fill feature can be used with formulas as well as with normal alphanumeric text.

To do so, first prepare your lists, tables, or sets of numbers. Then type one instance of the formula you need. Use your mouse to hover above the tiny black square in the lower right corner of the formula cell, and drag it across or up/down where you need it to go.
It will automatically copy the formula you entered into the new cells and apply the appropriate numbers to them from adjacent cells.

This feature can be used in any direction and basically any kind of formula, allowing you to quickly fill in numbers across your sheets with a minimum of time and effort.

Fill is one of the best features of Excel and is extremely easy to learn and use - spend any time at all with Excel and you will find yourself using it a great deal.