Whether you are writing a research paper for class or submitting an article for publication in a social science journal, you will have to follow APA style to format your paper. APA style provides guidelines not only on how to write and punctuate, but also on how to express and format numbers and percentages.

Step 1

Use the percent symbol after any number expressed as a numeral. For example: 12%. In APA style, numbers greater than nine are expressed as numerals and use the percent symbol.

Step 2

Use the word "percent" after any number expressed as a word. For example: five percent.

Step 3

Use the word "percent" after any number that begins a sentence, title or text heading. The AP rule for numbers is that you should begin a sentence with a word even if the number is greater than nine, and the word "percent" should also be used. For example: Forty-eight percent of the sample showed an increase.

Step 4

Use the percent symbol in tables and figures even if the symbol follows a number smaller than 10; APA style directs writers to use symbols in those cases to save space.

Step 5

Use the word "percentage" when you do not provide an exact number. For example: The student determined the percentage of rats that ate the food in the control condition.