Most rules for the use of numerals are based on the general principle that the reader comprehends numerals more readily than numerical word expressions, particularly in technical, scientific, or statistical matter. The following rules cover the most common conditions that require a choice between the use of numerals and words. Some of them, however, are based on typographic appearance rather than on the general principle stated above.
Arabic numerals are preferable to Roman numerals.
A figure is used for a single number of 10 or more with the exception of the first word of the sentence. 50 ballots 10 guns 24 horses nearly 13 buckets about 40 men 10 times as large Numbers and numbers in series 12.5. When 2 or more numbers appear in a sentence and 1 of them is 10 or larger, figures are used for each number. Petroleum came from 16 fields, of which 8 were discovered in 1956. At the hearing, only one Senator and one Congressman testified.