Abbreviating Number - Numbers and Percentages

AMA Manual of Style - Stacy L. Christiansen, Cheryl Iverson 2020

Abbreviating Number
Numbers and Percentages




No. of participants



The word number may be abbreviated No. in the body of tables and line art or in the text when used as a specific designator. Do not use the number sign (#) in place of the abbreviation; this could be confused with the hashtag (#) used in social media. The word number should always be spelled out when it is used as a proper noun (eg, Social Security number).

A No. 10 catheter was placed in the femoral artery.

She was No. 1 in her graduating class.

When referring to numbers of individuals in a study—in tables and figures as well as within parentheses—the abbreviation N is used when referring to the entire sample; n refers to a subsample (see 19.5, Glossary of Statistical Terms).

Patients were enrolled at each study site (N  =  2758) and randomly assigned to receive intervention (n  =  1378) or placebo (n = 1380).