Use hyphens in fractions whenever they are written as words, whether they function as a noun (two-thirds is more than one-half), adjective (a two-thirds majority) or adverb (two-thirds finished).

How is two thirds spelled?

Fractions as Words

For instance, we would write “2/3” as “two thirds”: He ate two thirds of the pizza by himself! This applies for most fractions.

Is it two thirds or 2 3?

2/3 = two thirds.