Numbers are formatted using either numerals or words depending on what they are conveying.
There are two general rules for using numbers in your text.
1) Write out numbers from one to nine.
There were four cars in the driveway.
2) Use numerals for 10 and above.
There were 10 cars parked at the side of the road.
There are exceptions to the general rules.
When comparing things with values above and below 10, choose one form — either numbers or numerals.
For 8 of the 12 courses… OR For eight of the twelve courses…
Use numerals for age, time, measurements, statistical functions, and dates.
a 6-year-old boy 11:45 8% May 7, 2014 4 cm of wood
Always use words to start a sentence.
There were 15 children in the class. Eleven of those children were painting.