 Fractions standing alone, or if followed by of a or of an, are generally spelled out.
Threefourths of an inch or threequarters of an inch (not ¾ inch or ¾ of an inch)
Onehalf inch or half an inch
Onehalf of a section (½ of a section)
Onefourth inch or a quarter of an inch
Onetenth
Seventenths of 1 percent
Onehundredth
Two onehundredths
Onethousandth
Three onethousandths
Twentyfive onethousandths
 Fractions are used in unit modifiers.
½inch pipe, not onehalfinch pipe.
½inchdiameter pipe
1½ to 2¾ pages
¾mile run
?point rise
3½ cans; 2½ times
 Do not use a comma in a builtup fraction of four or more digits or in decimals
(e.g., 1/3600).
 Use fractions (¼, ½, ¾, ?, ?, ?) or the mark with fullsized figures (1/2, 1/3600) only
if either is specifically requested.
