• I met seven people.
• John met 14 people.
• I was the eighth person.
• John was the 15th person.

Always spell out numbers at the start of a sentence. Reword sentences to avoid spelling out large numbers.

• Incorrect: 16 cars were parked on the street.
• Correct: Sixteen cars were parked on the street.
• Incorrect: 2134 children attended the school last year.
• Incorrect: Two thousand one hundred thirty four children attended that school last year.
• Correct: Last year, 2134 children attended that school.

Spell out round numbers and approximations.

• The tree is about sixteen feet tall.
• I have told you a thousand times not to do that.
• The car is worth less than six thousand dollars.

Round numbers and approximations greater than one million may be expressed with a combination of words and digits. Exact figures should be expressed using digits.

• The city was home to 3 million inhabitants.
• The city was home to 3 256 092 inhabitants.

Use digits for numbers used as nouns, exact measurements, decimal fractions, and percentages.

• Multiply the result by 5.
• The screws are 4 inches long.
• The best price for 4.5 m is $23.50.
• The sales tax was raised to 9%.

The International System of units (SI units), commonly known as the metric system, requires that digits be used with abbreviated units, and spelled-out numbers are used with spelled-out units.

• Incorrect: The road was 2 kilometres long.
• Correct: The road was 2 km long.
• Correct: The road was approximately two kilometres long.

Related numbers should be expressed consistently.

• Incorrect: He worked 40 hours the first week, and only seven the second week.
• Correct: He worked forty hours the first week, and only seven the second week.
• Correct: He worked 40 hours the first week, and only 7 the second week.

When two numbers are adjacent, spell out one of them. Usually, the one with fewer letters is spelled out.

• The couple had their choice of two 3-bedroom apartments.
• Another couple had to decide between 3 two-bedroom apartments.