Do you write 2.5 or 2 1/2? Is it $2,000 or $2,000.00? And if someone is the best, are they number 1 or No. 1? Some words about numbers:

Write out numbers from one to nine and use figures from 10 on. But write out the number if it starts the sentence.

Skip to section on this page:


Always use figures for temperature (20 C, -20 C), time, money, dates and addresses. No decimals (.00) with even dollar amounts: $1,500, not $1500. And no decimals with time of day: 2 p.m. or 4:30 a.m., not 2:00 p.m. Write noon or midnight to avoid confusion.

Write a compound adjective with a hyphen, as in a $20-million project. But write a project worth $20 million (no hyphen). Spell out $20 million rather than $20M, unless used in a headline.


Use figures for fractions: 2 1/2 days, not two-and-a-half days; 2.5 per cent, not two-and-a-half per cent.

Use figures when age stands alone after a person’s name: Timmy, 2, has two brothers, four and six.

Use figures in sequential designations, whether the noun is capped (Grade 7, Article 3, Highway 6) or lower case (page 3, paragraph 9, size 8). Note: If someone is the best at something, he or she is number 1 or No. 1, not number one. And it’s Day 1, not day one.


Refer to decades as the 2010s, not the 2010’s. In short form it’s the ’30s, not the 30s or 30’s. When writing about something that happened in the middle of the 1930s, use mid-1930s or shorten to mid-’30s. But a person who is 35 is in his/her mid-30s.


When approximating an amount of money, a number of people, etc., look to round up or down. Don’t write: The concert drew about 258 people. Here, 258 people is an exact number. Either delete “about” or round off. Write: The concert drew almost 260 people. Or: about 250 people.

Write “about” rather than the longer “approximately.” And write “more than” or “less than,” not “over” or “under.”


Don’t forget the comma in numbers larger than 999: 1,000, not 1000.

Phone Number Format

Write campus phone numbers and extensions as: 519-824-4120, Ext. 53864.

Check CP Style for metric symbols and usage.