General Rules
* Numbers 1-9: Spell out numbers one through nine.
* Numbers 10 and above: Use numerals.
* Start a sentence with a numeral: If you must start a sentence with a number, spell it out.
Exceptions
* Dates: Always use numerals (e.g., 1990, July 4, 2023).
* Ages: Use numerals (e.g., 5-year-old).
* Measurements: Use numerals (e.g., 2 cm, 10 pounds).
* Percentages: Use numerals (e.g., 25%, 100%).
* Fractions: Use numerals (e.g., 1/4, 2/3).
* Decimal numbers: Use numerals (e.g., 0.5, 1.25).
* Statistics: Use numerals (e.g., mean = 3.5, p < 0.05).
* Scores and rankings: Use numerals (e.g., scored 12 points, ranked 3rd).
* Money: Use the dollar sign and numerals (e.g., $5, $10.50).
* Addresses: Use numerals (e.g., 123 Main Street).
* Times: Use numerals (e.g., 9:00 AM, 10:30 PM).
* Equations: Use numerals for all numbers in equations.
* Tables and Figures: Use numerals for all numbers in tables and figures.
Example
Here's a sentence that demonstrates the rules:
> The study involved 23 participants, with an average age of 35 years. Two of the participants scored above 90 on the test, while three scored below 60. The results were statistically significant (p < 0.05).
Consistency is Key
Within your paper, try to maintain consistent use of numerals and spelled-out numbers. Avoid switching back and forth unless there's a strong reason to do so.
Let me know if you have any more questions or need further clarification on any specific number use in your paper.