1-1 may refer to:
*
New Year's Day
New Year's Day is a festival observed in most of the world on 1 January, the first day of the year in the modern Gregorian calendar. 1 January is also New Year's Day on the Julian calendar, but this is not the same day as the Gregorian one. Wh ...
, a public holiday in many countries, held annually on the first of January
*
Schweizer SGP 1-1, an American glider design
*
World 1-1, the first level of Nintendo's ''Super Mario Bros''
See also
*
One-to-one (disambiguation)
One-to-one or one to one may refer to:
Mathematics and communication
*One-to-one function, also called an injective function
*One-to-one correspondence, also called a bijective function
*One-to-one (communication), the act of an individual comm ...
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