When to Spell out Numbers?

The general rule is that you should spell out numbers one to one hundred, and use digits for anything higher than that. Also hyphenate numbers that that are made up of two words (“thirty-seven”). You should also spell out other round numbers like “thousand,” “hundred thousand,” “billion,” and “trillion.”

When should you write numbers as words?

In general, words should be used for numbers from zero through nine, and numerals should be used from 10 onwards. This is true for both cardinal numbers (e.g., two, 11) and ordinal numbers (e.g., second, 11^th). However, there are some important exceptions to this rule.

When should you not spell out numbers?

Writing Small and Large Numbers

A simple rule for using numbers in writing is that small numbers ranging from one to ten (or one to nine, depending on the style guide) should generally be spelled out. Larger numbers (i.e., above ten) are written as numerals.