In general, write out numbers one through nine. Use figures for 10 or above and whenever preceding a unit of measure or referring to dates, military units, ages of people, animals, events or things. Also in all tabular matter, and in statistical and sequential forms.

He is 5 feet 6 inches tall.

The cadet gave his little brother the top three reasons to attend The Citadel.

She has a 6-year-old.

Her daughter is 4 years old.

Yesterday 1st Lt. Smith gave the command.