"There are three rules for writing a novel," W. Somerset Maugham once wrote. "Unfortunately, nobody knows what they are."

If I had to adapt Maugham's quip to business, scientific and technical writing, I would say, "There is one rule for writing numbers. Fortunately, everyone knows what it is."

Do you?

It's simple: Be consistent.

Here are eight guidelines to help you follow that one simple rule:

1. Spell out numbers less than 10; use figures for numbers 10 and higher (except in scientific and technical writing, where all numbers may be written as figures).

One potato, two potatoes, three potatoes, four — makes 10 potatoes.

2. Spell out numbers that appear as the first word in a sentence (or restructure the sentence to avoid beginning with a number).

Sixty-four bottles of beer were on the wall, 64 bottles of beer.

3. Use figures for percentages (even for percentages less than 10).

We spent 8% of our day putting those bottles on the wall.

Note: Scientific and technical writers prefer the percent symbol, whereas business writers have traditionally preferred the word percent, but increasingly business writers are using the symbol.

4. Use figures for monetary amounts (even for amounts less than 10).

If one of those bottles happens to fall, it will cost you $8.57.

5. Omit the decimals or zeros in even dollar amounts (except for consistency in a table or series).

We'll round that figure up to an even $9 ($6.57 for the beer, $2.00 for the bottle and $.43 for our boat payment).

6. Write dates as cardinals (even though you pronounce them as ordinals).

The breakage occurred on the evening of December 1, not December 1st.

7. Don't repeat a spelled-out number in figures (even in legal writing).

You have three days to request your four refunds from these two breweries, not You have three (3) days to request your four (4) refunds from these two (2) breweries.

8. Present a series of numbers in the same relative order.

We broke three bottles on the first day, two bottles on the second and one bottle on the third, not We broke three bottles on the first day, two bottles on the second and on the third one bottle.

In addition to these guidelines, here's a little trick I learned from some technical writers. To sound more precise and more in command of your facts, use more than and less than rather than over and under when referring to amounts. For example, "We spent more than $2 million on this project," not "We spent over $2 million on this project."

Regarding creative writing, I think Maugham had a point. There's no simple formula for writing something as complex as a novel, but if I were to take a stab at it, I'd say, (1) write about something you care about, (2) write in a way that makes your readers care and (3) after all your planning, researching and outlining, follow your imagination.

And while we're on the topic of numbers and the imagination, for a fun novel that combines the two, I recommend Yoko Ogawa's "The Housekeeper and the Professor."

Stephen Wilbers offers training seminars in effective business writing. E-mail him at wilbe004@umn.edu. His website is www.wilbers.com.