numbers: round numbers

Write out numbers used figuratively:

• a thousand and one excuses
• “They may attack me with an army of six hundred syllogisms.” (Erasmus)
• “And torture one poor word ten thousand ways.” (Dryden)

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:

• 550 thousand (instead of 550 000)
• 23 million
• There were more than 2.5 million Canadians between the ages of 30 and 40 in 1971.

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:

• three million people

but

• 3.1 million people
• $3 million

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:

• one hundred and fifty-two thousand three hundred and five

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

• nineteen hundred and ninety-six (1996)