Rules for writing numbers: Spelling out numbers

• Spell out numbers:

  • Spelling out Round numbers
  • Write a numbers Beginning a sentence
  • When to spell out Mixed numbers
  • Spelling out Compound numbers.
  • Writing out Centuries

• Use numerals in writing numbers for...
• Making plurals out of numbers

Numbers in nontechnical contexts, the following are spelled out: whole numbers from one through one hundred, round numbers, and any number beginning a sentence. For other numbers, numerals are used

Spell out numbers:

1. Spelling out Round numbers. By virtue of their rounding, these numbers are imprecise. They are written out.
2. Beginning a sentence. When numbers or a date are required to open a sentence, write them out.
3. Mixed numbers? Do not mix numerals with written numbers when they refer to similar things
4. Spell out Compound numbers. Hyphenate compound numbers from twenty-one to ninety-nine and the written form of fractions.
5. Writing out Centuries. Write out references to centuries, the eighteenth century, the twenty-first century, in lower cased letters.

Use numerals for

1. Numbers 10 and above, or numbers under 10 grouped with numbers 10 and above (for example, from 6 to 12 hours of sleep).
2. Exact statistical measures, scores, sample sizes, and sums (multiplied by 3, or 5% of the sample).
3. Physical measures are given in the metric system following the International System of Units

To make plurals out of numbers, add s only, with no apostrophe (the 1950s).