numbers: round numbers

Write out numbers used figuratively:

Numbers with a long succession of zeros, as well as numbers in the millions or higher, should be written as a combination of words and figures:

However, note that if the number preceding million, billion, etc., is a whole number below 10 that is not used with a unit of measurement, it is usually spelled out:

but

Numbers are normally rounded to no more than three significant digits. Thus 2 653 000 becomes 2.65 million, not 2.653 million.

The proper form for large numbers that must be written in full is as illustrated:

The practice of writing a number in full and then repeating it in numerals in parentheses should be reserved for legal documents: