The numerical value of true in many programming languages. 1 is the ASCII code of "Start of Header". In science
Dimensionless quantities are also known as quantities of dimension one. 1 is the atomic number of hydrogen. +1 is the electric charge of positrons and protons. Group 1 of the periodic table consists of the alkali metals. Period 1 of the periodic table consists of just two elements, hydrogen and helium. The dwarf planet Ceres has the minor-planet designation 1 Ceres because it was the first asteroid to be discovered. The Roman numeral I often stands for the first-discovered satellite of a planet or minor planet (such as Neptune I, a.k.a. Triton). For some earlier discoveries, the Roman numerals originally reflected the increasing distance from the primary instead. In philosophy
In the philosophy of Plotinus (and that of other neoplatonists), The One is the ultimate reality and source of all existence. Philo of Alexandria (20 BC – AD 50) regarded the number one as Gods number, and the basis for all numbers ("De Allegoriis Legum," ii.12 [i.66]). The Neopythagorean philosopher Nicomachus of Gerasa affirmed that one is not a number, but the source of number. He also believed the number two is the embodiment of the origin of otherness. His number theory was recovered by Boethius in his Latin translation of Nicomachuss treatise Introduction to Arithmetic.
In sports
In many professional sports, the number 1 is assigned to the player who is first or leading in some respect, or otherwise important; the number is printed on his sports uniform or equipment. This is the pitcher in baseball, the goalkeeper in association football (soccer), the starting fullback in most of rugby league, the starting loosehead prop in rugby union and the previous years world champion in Formula One. 1 may be the lowest possible player number, like in the American–Canadian National Hockey League (NHL) since the 1990s or in American football. In other fields
Number One is Royal Navy informal usage for the chief executive officer of a ship, the captains deputy responsible for discipline and all normal operation of a ship and its crew. 1 is the value of an ace in many playing card games, such as cribbage. List of highways numbered 1
List of public transport routes numbered 1
1 is often used to denote the Gregorian calendar month of January. 1 CE, the first year of the Common Era
01, the former dialling code for Greater London (now 020)
For Pythagorean numerology (a pseudoscience), the number 1 is the number that means beginning, new beginnings, new cycles, it is a unique and absolute number. PRS One, a German paraglider design
+1 is the code for international telephone calls to countries in the North American Numbering Plan.