Which tool would you use to quickly fill adjacent cells with the same content?

The fill handle is the correct tool to use for quickly filling adjacent cells with the same content in a spreadsheet. This tool allows you to click and drag a small square located at the bottom right corner of a selected cell. By dragging the fill handle over adjacent cells, you can easily replicate the content of the original cell into the selected range.

Using the fill handle is particularly efficient for tasks that require consistency across multiple cells, such as filling down a series of data or repeating a specific value. It is a fundamental feature that enhances productivity by simplifying the process of data entry and ensuring uniformity.

In contrast, other tools mentioned serve different purposes. The merge button is primarily used to combine multiple cells into one larger cell, which does not assist in filling adjacent cells with identical content. The currency button formats numbers as currency but doesn’t help in filling cells with data. The undo button, on the other hand, is used to revert changes made in the spreadsheet rather than to fill cells with content.