Most style guides call for spelling out numbers less than 10, and using numerals for those 10 and over. While reading a magazine today, I saw the phrase nine out of 10, and it struck me as wrong even though it technically adheres to the standard. It seems like an exception is called for in this case, instead of the distracting mixing of word and numeral. Do style guides address this issue?
The Oxford Public Affairs Directorate Writing and Style Guide (PDF) says
Do not mix the two styles within a paragraph when they refer to the same category
and gives as acceptable examples
- At least 8 of the 20 students were not concentrating
- Eight of the twenty students were not concentrating
- In general, 8 or 10 students were present at all three lectures
I think this is sensible.