5. Numbers
5.2 Numbers and punctuation
5.2.1 Numbers and decimal points
Use a point, not a comma, before a decimal.
0.25
5.5
5.2.2 Numbers and commas
In numbers of one thousand or more, use commas between groups of three digits, counting from the right.
2,436
32,548
83,200,000
Do not use commas in serial numbers such as page numbers, street numbers and years.
All further enquiries should be made at our office at 1558 Brunswick Avenue, New York City.
5.2.3 Numbers and hyphens
Hyphenate numbers from twenty-one to ninety-nine.
Three hundred and forty-six students are enrolled in the School of Fine Art.
Spell out numbers that are joined to a word by a hyphen, except in the case of set phrases such as 24-hour clock.
A five-year period
A one-week holiday
When two numbers appear side by side, spell one of them out. If one of them occurs alongside a unit of measurement, make that one a numeral.
four 6-week periods
thirty-six 20-cent coins