COMPUTER SYSTEMS RESEARCH
Elements of Technical Writing
2005-2006

  • >Place a hyphen between a number and unit of measure when they modify a noun
    1. When a number and unit of measure are compounded to form an adjective, they are separated by a hyphen 
       2-week-old culture
 15,000-volt charge
 12-inch-long ruler
    2. No hyphen is used between the number and unit of measure when they do not form a compound adjective 
          The feed-pipe section goes on for 47 feet...
    
    ...47-foot-long feed-pipe...
    3. Note that all numbers with units of measure are written as numerals (from Rule 1)
    4. Leaving out the hyphen between the number and unit of measure is one of the most common mistakes technical writers make.