How numbers are treated in a text can be quite different in different fields of study, but there are some general rules about the use of numbers and numerals within the flow of text.
Small numbers (less than 20) are usually spelled out, while large numbers are given as numerals.
On two previous occasions he had been named for missions abroad.
The archaeological material presented in this paper consists of 59 runic artefacts.
Numerals are used when the exact value of the number is important, even if that value is small.
Samples were kept in 1 ml tubes on ice for 2 min and remaining tissue debris was removed by centrifugation at 13,200 x g for 3 min.
A (small) number should be spelled out if it is the first word in a sentence, especially if the value is less than 20, but other numbers may be given as numerals in the same sentence. In general, it is best to avoid starting a sentence with a numeral.
In total, 28 names appear in the material. Thirteen can be categorized as male names and 12 are probably female names. Two transliterated names could belong to either gender.
Note that the word “one” is often used as a pronoun, and in this usage, it must be spelled out and cannot be replaced by a numeral.