CCLXVI

CCLXVI is the Roman numeral representation of the integer 266. In the Roman numeral system, C is 100, L is 50, X is 10, V is 5, and I is 1, and the numeral is formed by adding the values of these letters in descending order. The figure 266 has appeared in a number of historical and contemporary contexts.

In the Julian calendar, the year 266 AD was a period of the Roman Empire marked by the reign of Emperor Gallienus, who faced external threats from Germanic tribes and internal challenges from usurpers. The same integer is used to identify chapters, sections, and volumes in many bibliographic, legal, and academic works; for example, a standard reference series might denote its 266th volume as "CCLXVI."

In the military, unit numbers sometimes employ Roman numerals, so a designation such as "Unit CCLXVI" would refer to the 266th unit in a sequence. Similarly, in the context of celestial bodies, the trans‑Neptunian object numbered 266 in the Minor Planet Center’s catalog is sometimes listed in specialized databases with the designation 266CCLXVI to signify its numeric order.

The number 266 also appears in music cataloguing; composers often use opus numbers to identify individual works, and Op. 266 would indicate the 266th published composition of a given composer.

Overall, CCLXVI serves as an unambiguous, compact way of expressing the ordinal number 266 and is used wherever Roman numerals remain common for enumeration, especially in archival, bibliographic, and administrative contexts.