Q. This has to do with page ranges for a bibliography, as described in CMOS. It is clear that 125–29 is correct and 125–129 is not. However, it is not clear what to do with a range like 145–155. Should it be 145–55 or 145–155? The trouble comes from the part of the explanation that reads “use two or more digits as needed” and the lack of examples to address this particular situation. I would think 145–55 is sufficient, but then, I don’t trust my own intuition because 125–9 seems sufficient to me, too. And that is wrong. Please help!

A. Using “two or more digits as needed,” a rule of thumb for certain inclusive numbers, means using more than one digit but no more digits than you need: 145–155 uses more digits than you need, and 125–9 uses only one digit, so 145–55 and 125–29 are Chicago’s preferred style. However, 145–155 (using all digits) and 125–9 (using only the digits that change) are also perfectly good styles; CMOS includes them as alternatives.