91
Học thuậtThân thiện
Definition
- Adjective:
- Being one more than ninety: The number 91 is the natural number that follows 90 and precedes 92. It is an odd number and can be represented as XCI in Roman numerals.
Usage
- As a determiner or adjective: Used to describe a quantity of exactly ninety-one items, years, units, etc.
- There are 91 days in a typical quarter.
- My grandmother is 91 years old.
Advanced Usage
- In mathematics: 91 is a semiprime number (7 × 13) and a centered hexagonal number.
- The factors of 91 are 7 and 13.
- In other contexts: Often used to denote a specific identifier, such as a model number, highway designation, or atomic number.
- Interstate 91 runs through New England. (Here, '91' is part of a proper noun, 'Interstate 91').
- Protactinium has the atomic number 91.
Variants and Related Words
- Ninety-one: The word form of the numeral.
- He scored ninety-one points.
- XCI: The Roman numeral representation.
- The year XCI in ancient history.
Synonyms
- XCI (Roman numeral equivalent).
- Ninety-one (word form equivalent).
Related Phrases
- '91' as part of a compound term: When used in names, titles, or codes, it functions as a numeral within a larger identifier.
- The Class of '91 had a reunion. (Here, '91 is a shortened form for the year 1991).
- She drove a '91 Mustang. (Here, '91 is a shortened form for the model year 1991).
Adjective
- being one more than ninety