It's the eternal question. Should you spell your numbers out? As in:
I ate three cartons of Ben & Jerry's.
Or let numerals do the work? As in:
I ate 3 cartons of Ben & Jerry's.
The most important point to keep in mind is this: they were the teeny-tiny, single serving cartons, like the kind they sell for kids. Really small. That's all I'm saying.
As for spelling out numbers, the big rule is Be consistent. Pick a system and stick to it. If you're writing for a specific publication, ask for their style guidelines. Otherwise, your best bet is to follow APA style guidelines:
- Never start a sentence with a numeral:
Five little monkeys jumped on the bed.
5 little monkeys jumped on the bed.
- Spell out numbers under ten, except when
• Referring to a specific address:
Number 5 Cherry Lane
• Naming an age, time, or date:
She left for London with her 8-year-old on August 6 at 9:00 am.
• Offering a precise measurement or reporting a quantitative result:
The gold weighed 5 grams.
Average of 4.5 on a 7-pt. Likert scale.
• Directing the reader to a specific page or figure in a book:
Table 4 on page 7.
• Grouping or comparing with numbers > 10:
According to 6 of 40 dentists surveyed.
6 cake mixes, 2 large cake tins, and 20 cans of soda.
- Use numerals for numbers 10 and above, except:
• At the beginning of a title or sentence:
Twenty Blackbirds: A Novel
• For common phrases
• For common fractions:
three fourths of a pie
• When referring to very large sums. (In this case mixing words and numerals is preferred.)
a population of 315 million
- Do not stick to the rules where the rules will make things confusing.
• This phrase is confusing:
6 5-year-old boys
On a quick read it looks like:
65-year-old boys (= pretty weird)
• Either of the following is acceptable:
Six 5-year-old boys.
6 five-year-old boys.