Q. In sports, does the score require a hyphen or should you use an en dash? What about decisions on the Supreme Court?
A. Let’s say the Washington Wizards beat the Los Angeles Lakers 100–99. Normally, the en dash is used to express a range—from x up to and including y. The expression 100–99 does not express a range—it expresses two separate values. Nonetheless, we’ve decided that because we say “one hundred to ninety-nine,” an en dash is better than a hyphen. In the same vein, when the Supreme Court decides something five votes to four, use an en dash rather than a hyphen: 5–4 (not 5-4). For a fuller statement of the rule and more examples, see paragraph 6.78 in CMOS 16.