Percentages and decimal fractions - Numbers - Part III. Style 20 spelling

A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Percentages and decimal fractions
Numbers
Part III. Style 20 spelling

Use numerals to express percentages and decimal fractions, except at the beginning of a sentence (see 23.1.2). Spell out the word percent, except when you use many percentage figures and in the sciences, where the symbol % is usually preferred (with no intervening space after the number). Notice that the noun percentage should not be used with a number.

Scores for students who skipped summer school improved only 9 percent. The percentage of students who failed was about 2.4 times the usual rate.

Within this system, the subject scored 3.8, or 95%.

but not

The average rose 9 percentage points.

When you use fractional and whole numbers for the same type of item in the same sentence or paragraph, give both as numerals.

The average number of children born to college graduates dropped from 2.4 to 2.

Put a zero in front of a decimal fraction of less than 1.00 if the quantity expressed is capable of equaling or exceeding 1.00; otherwise, omit the initial zero.

a mean of 0.73

a loss of 0.08

p < .05

For fractions standing alone, follow the general rule (see 23.1.1) for spelling out the parts. If you spell the parts, include a hyphen between them. Express in numerals a unit composed of a whole number and a fraction, with no intervening space between these items.

Trade and commodity services accounted for nine-tenths of all international receipts and payments.

One year during the Dust Bowl era, the town received only 15/16 of an inch of rain.

The main carving implement used in this society measured 2½ feet.