One, two, three, four, five… Everybody in the car so come on let’s ride. -Mambo №5
These are the familiar lyrics to Lou Bega’s version of Mambo №5, released in 1999. While the song may be catchy, the title doesn’t fit the grammar rule for writing numbers.
On the surface, writing with numbers is a simple rule: write out numbers between zero and nine. However — as it is with all grammar — as you dig, the layers get complicated.
The Simple Rule
The AP Stylebook refers to numbers as “figures”. Their base rule is to write out figures between zero and nine.
- I ate four of the 12 donuts for breakfast.
- She owns two houses.
- There is zero chance I finish this story.
There are many exceptions to the AP’s simple rule. The exceptions depend on usage of the figure and the context of the sentence.
Ignore the Simple Rule and use figures when writing addresses. Only spell out the full word when referring to numeric street names nine/ninth and under.
- She owns 3 Maple Street.
- I live at 456 Ninth Avenue.
- He wants to buy the property at 789 18th Street.
When referring to ages, ignore the simple rule and use figures.
- The 7-year-old boy has a cousin who is 8 years old.
The only exception with ages comes when the figure begins a new sentence.
- Twenty-somethings are giving 30-somethings a run for their money in this economy.
Beginning a Sentence
Spell out figures that begin a sentence, regardless of the number.
- Four people ate 4 donuts at the counter.
Spell out figures when using common phrases.
- She said to him, “one bird in hand is worth two in the bush” despite not understanding what it meant.
Use figures when writing dates unless referring to centuries nine and under.
- What comparisons can be drawn between 80s popular culture and that of the first century?
Use numeric figures for decimals, fractions, and percentages greater than one. Write out the figures for anything less than one.
- We ate two-thirds of the donuts and before running 1.5 miles.
When referring to any denomination of money, ignore the simple rule and use figures.
- She wrote a check for $2.37. Who does that?
Ship names ignore the simple rule. Always use numeric figures when referring to the names of ships. The only exception is “Air Force One”.
- Apollo 1 never left the launch pad and almost ended the space program while Apollo 11 changed the world forever.
While Mambo №5 might be a catchy song, its name doesn’t comply with the AP rule regarding figures. Maybe someone will remix the song with the proper title: Mambo No. Five.