Style guides differ on some points involving the use of numerals (i.e., for example, 16 and 44 instead of sixteen and forty-four) in texts, but there are two rules on which most agree: (1) Spell all integers from zero to ten. (2) Use numerals for numbers 11 and above. Some publications make the cut at nine instead of ten, but most do have a consistent policy.
In practice, there are a few common exceptions—namely:
(a) Numerals are usually used for all numbers in texts involving math, formulas, or calculations.
(b) Numerals are used for measurements—for example:
Mr. Blake, who is described as being 6 feet 8 inches tall and weighing 230 pounds, has 11 prior arrests … [Wall Street Journal]
(c) Substitute words for long rows of zeros, especially million, billion, and so on (many publications don’t spell out thousand). Use numerals for one through ten when they precede million, billion, etc.—for example:
Macquarie Group Ltd. expects production to drop a further 4 million tons this year. [Bloomberg]
(d) Spell out all numbers that begin sentences (except when the number is a year)—for example:
Two hundred and fifty years ago Samuel Johnson disparaged “an unnecessary word which is creeping into the language”. [The Guardian]
(e) Use numerals for scores—for example:
The Stars pounded their way out of a three-goal hole for a 4-3 victory in a shootout at American Airlines Center. [Chicago Sun-Times]