#### Step one: Input Your Formula in the Top Cell

Suppose you have a column of data to sum up. The initial step is entering your formula into the top cell of the column. For instance, the formula might be "=SUM(A1:A5)".

#### Step two: Choose the Cell Containing the Formula

Once the formula is entered, select the cell holding it. You can click on the cell or utilize the arrow keys on your keyboard. Once the cell is chosen, a small black square appears in the bottom-right corner.

#### Step three: Pull the Cell Down

After selecting the cell with the formula, drag it down to the column's bottom. Click on the small black square, drag it downwards, and observe the formula being duplicated into the cells below. Upon reaching the column's end, release the mouse button.

#### Step four: Verify Your Outcomes

Once the formula is duplicated down, inspect the column's cells. In this case, the cells should display the sum of data in each row. If errors are present, amend them by editing the formula in the top cell.

#### And that's all there is to it!

Now you've learned how to employ the "copy down" function in Excel. This feature is useful when you need to apply the same formula to an entire column of data. Remember to review your outcomes after duplicating the formula to ensure accuracy.