Do not start a sentence with a numeral. Spell out the number or reword the sentence to start with a different word.
(E.g., 472 soldiers came to the memorial
à
Four-hundred seventy-two soldiers came to the memorial
à
The
memorial welcomed 472 soldiers.)
When the general rule gives you a combination of numbers in numerals and written out numbers within the same
phrase, change them all to numerals. (E.g., there were four to 13 variables
à
there were 4 to 13 variables.)
If a chunk of text has many written numbers or a combination of both forms in a small space, to facilitate reading,
opt to change them to numerals despite the general rule.
except
Add “s” for plural
Add an “s” to a numeral, or “es” or “s”
to the written out form.
twos, sixes, 60s, 13s, the 1980s
Writing with Numbers
Chicago Manual of Style General Rule*:
For scientific and statistical
contexts:
1% 75% 63%
Written with the word percent
for non-technical contexts:
one percent
seventy-five percent
sixty-three percent
Uncommon fractions use
numerals:
1/77 7/30 8/11
Common fractions are written:
a half
two-thirds
three-quarters
If the measurement is written
out, follow the general rule:
six miles, 110 kilograms, nine
centimeters
If the measurement is
abbreviated
use numerals:
6 mi, 110 kg, 9 cm
Month day, year
April 6, 1990
Decades
1990s, ’90s, the nineties
Follow the general rule for
centuries:
the twenty-first century
Use scientific notation:
422 x 10^-7
Or use prefixes:
micro-, nano-, pico-, etc.
5.3 million
7 billion
1 trillion
Use scientific notation:
83 x 10^15
Or use prefixes:
mega-, giga-, tera-, etc.
Other Number Tips:
%
percentages fractions
very small numbers
large numbers very large numbers
measurements dates
Numeral +
million
billion
trillion
#s
Ordinals (first, second, third, etc.)
Follow the general rule for writing out or using numerals.
Do not use as a day when the month is also mentioned.
May 25
th
, 2004à May 25, 2004
For military units, follow the general rule.
The Twenty-eighth Brigade
The Second Armored Brigade Combat Team
Letters in ordinals (-st, -nd, -rd)
are not superscripts.
Add “s” for plural
Add an “s” to a numeral, or “es” or “s”
to the written out form.
twos, sixes, sixties, 300s, the 1980s
#s
Currency
Write out the long-hand name of uncommonly known currencies
at first use, and then use the abbreviation for that currency.
three hundred Canadian dollars = C$300 or Can$300
$749 New Zealand dollars = NZ$749
$15.69 Australian dollars = A$15.69
ninety-eight Mexican pesos = Mex$98
50 euros = €50 (EUR 50)
332 yen = ¥332 (JPY 332)
55.5 bitcoins = BTC 55.5 (XBT 55.5)
100 yuan renminbi (100 yuan) = ¥100 or RMB 100 (CNY 100)
Source:
University of Chicago Press. The Chicago Manual of Style. Chicago, IL: University of Chicago Press, 2017.
Zero – one hundred = written
101+ = numerals
*Many publications choose to follow the alternative general rule: zero – nine = written; 10+ = numerals. Check the publisher’s preference.
