Which method allows users to conditionally format cells based on numeric values only?

The method that allows users to conditionally format cells based on numeric values is by numbers. This approach enables users to set specific formatting rules that apply when the values in the cells meet certain numeric criteria, such as being greater than, less than, or equal to a specified number. For example, users might highlight all cells that contain sales figures exceeding a target amount, effectively allowing for visual data analysis.

The option focusing on images relates to formatting based on graphical representations, which is not dedicated to numeric values. The methods that pertain to text and dates primarily concern the formatting based on alphanumeric characters or chronological values, rather than quantifiable data. Hence, the ability to conditionally format cells specifically by numeric values ensures that the formatting accurately reflects the data's analytical needs.