Dieciséis

Dieciséis is the Spanish cardinal number that denotes the integer 16. It is used in counting, dates, measurements, and arithmetic. It appears in everyday language, mathematics, and writing and is the first of the numbers from 16 to 19 that use the dieci- prefix.

Etymology: The name derives from the combination of diez (ten) and seis (six). In Old Spanish the form fused into dieci- and later dieciséis for the specific 16, following the general pattern for 16–19: diecisiete, dieciocho, diecinueve. The construction reflects the influence of Latin sedecim (sixteen) on Romance languages, though the modern Spanish form is based on diez plus seis.

Pronunciation and spelling: The word is spelled dieciséis and is stressed on the final syllable in standard Spanish. It is part of a group of numbers that share the dieci- onset, with diecisiete, dieciocho, and diecinueve following the same pattern.

Numerical properties: In base-10, dieciséis is even and a composite number. It is 4 squared (4^2). In Roman numerals it is XVI. In binary, 16 is 10000, and its prime factorization is 2^4.

Usage and forms: Dieciséis appears in dates, such as dieciséis de mayo, and in lists or sequences. The ordinal form is decimosexto. For related purposes, see also Spanish numbers and numerals.