Writing Style – Rules for Numbers

Laura’s question: “How do you write numbers in sentences? Do you spell out the number or can you write 10. Are there different rules if the sentence starts with a number?”

BizWritingTip response: The guideline for writing numbers in sentences is to spell out numbers from one to nine. Ten and over you use figures.


Three computers

10 pens

Two policies?1

5th hole

The new employees were all born in the ‘80s.

Now for the exceptions to the rules —

Use figures, when writing addresses, ages, measurements, page and figure numbers, votes, scores, clock times, money amounts, and measurements.


3 Bay Street

Children aged 6-9

4 p.m.


Page 9

If you start a sentence with a number, you must spell it out.


Four people arrived late.

Thirty to 40 people is all the room will hold.

When writing about years, reorganize your sentence so it does not begin with the year.

If you are writing numbers in a casual fashion, use words.


The book was read by thousands.

Please note: In business writing, you should never write numbers both ways.


We require 8 (eight) copies of the report. (incorrect)

We require eight copies of the report. (correct)