3 Common Errors When Using Numbers
References to numbers, spelled out or in numeral form, often include erroneous use of hyphens or dashes, as shown in the following examples. Errors are explained and corrected in the discussion and revision that follows each sentence.
1. The US men’s basketball team won seven Olympic gold medals between 1936–68.
A dash (not a hyphen) that connects two numbers to represent a range functions as a replacement for from and to, so do not include from before a number range separated by a dash. Between, likewise, should not be paired with a number range, but in this case, retain the word, pairing it with and in place of the dash: “The US men’s basketball team won seven Olympic gold medals between 1936 and 1968.” (“The US men’s basketball team won seven Olympic gold medals 1936–68” is not syntactically valid.)
2. Fourteen and fifteen-year-old kids are easily impressionable.
When two hyphenated phrasal adjectives are identical except for the first term, the rest of the first phrasal adjective after that term can be elided, with the implication that the balance of the second phrasal adjective serves both of the initial words. However, to signal this sharing, retain the hyphen after the first element: “Fourteen- and fifteen-year-old kids are easily impressionable.” (Otherwise, the implication is that fourteen kids are easily impressionable, and so are fifteen-year-old kids.)
3. The rockslide occurred when a massive slab measuring fifty-by-eighty-by-fifteen feet broke off from a sheer cliff and went flying down the mountain.
When a phrase consisting of two or more numbers separated by by describes the surface area or volume of an object, omit hyphens unless the entire phrase modifies a noun: “The rockslide occurred when a massive slab measuring fifty by eighty by fifteen feet broke off from a sheer cliff and went flying down the mountain.” (Compare “The fifty-by-eighty-by-fifteen-foot slab broke off from a sheer cliff and went flying down the mountain.”) The same rule applies when numerals represent the numbers.