Use of numbers

[Malcolm]

What are the hard and fast rules for using numbers in fiction text?

For instance, a person's age is usually two digits. I find that one or two digits is best written in words, ie. twenty three instead of 23.

But for three or more digits, I find that writing the Arabic numerals is more accessible, ie. 173 degrees southwards instead of one hundred seventy three degrees southwards.

[K.P.]

my comp teacher told me that use numbers in the story, but write it out in dialogue. The exceptions were in the number of thousands as long as they were in tens.

e.g. "I'm only twenty-three," admitted Bob.
Susan entered room 48 and took a seat at a nearby desk.
Johnny missed his favorite horse, housed two-thousand miles away at his aunt's farm.
Cookie thought the monument was to span 5,280 feet, only to find it was done in inches. It was not as impressive as she dreamed.

[Philip]

Mixed view on this, my editor wanted all numbers written out. Five million is OK rather than 5,000,000 but when it's an exact number it looks clunky i.e the feet example above would look silly as five-thousand-two-hundred and eighty feet. The dashes use also is confusing and seems to be inconsistently handled by grammar systems in software. Plus it varies even in traditionally published books from both sides of the Atlantic

[K.P.]

eh, true. it all depends on the editor and what system of english you're using XD