Which APA format rule pertains to the use of numbers in writing?

The guideline regarding the use of numbers in APA format emphasizes that numbers below ten should generally be written as words. This is an important rule designed to enhance clarity and readability in academic writing. For example, writing "five participants" is typically preferred over using the numeral "5" when the value is less than ten.

Following this rule helps maintain consistency throughout a document and aligns with the conventions of the APA style, which aims to create a reader-friendly experience. Numbers that are ten or greater are generally expressed as numerals, making it easy for readers to quickly grasp larger quantities. Additionally, using numerals for statistical references is more context-specific, depending on the data's nature and presentation.

Consequently, writers should also avoid starting sentences with numerals to maintain the flow of the text. Overall, this guideline is crucial for authors wanting to present their work clearly and professionally in accordance with APA standards.