1 (number) 1 | −1 0 1 2 3 4 5 6 7 8 9 →List of numbers — Integers0 10 20 30 40 50 60 70 80 90 → | Cardinal | 1 one | Ordinal | 1st first | Numeral system | unary | Factorization | | Divisors | 1 | Greek numeral | α' | Roman numeral | I | Roman numeral (Unicode) | Ⅰ, ⅰ | Persian | ١ - یک | Arabic | ١ | Ge'ez | ፩ | Bengali | ১ | Chinese numeral | 一,弌,壹 | Korean | 일, 하나 | Devanāgarī | १ | Telugu | ೧ | Tamil | ௧ | Kannada | ೧ | Hebrew | א (alef) | Khmer | ១ | Thai | ๑ | counting rod | | prefixes | mono- /haplo- (fromGreek)uni- (from Latin) | Binary | 1 | Octal | 1 | Duodecimal | 1 | Hexadecimal | 1 |
1 (one; /ˈwʌn/ or UK /ˈwɒn/) is a number, a numeral, and the name of the glyph representing that number. It represents a single entity, the unit ofcounting or measurement. For example, a line segment of "unit length" is a line segment of length 1.
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As a number
One, sometimes referred to as unity, is the integer before two and after zero. One is the first non-zero number in the natural numbers as well as the firstodd number in the natural numbers.
Any number multiplied by one is that number, as one is the identity for multiplication. As a result, one is its own factorial, its own square, its own cube, and so on. One is also the empty product, as any number multiplied by one is itself, which produces the same result as multiplying by no numbers at all.
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[edit]As a digit
The glyph used today in the Western world to represent the number 1, a vertical line, often with a serif at the top and sometimes a short horizontal line at the bottom, traces its roots back to the Indians, who wrote 1 as a horizontal line, much like the Chinese character 一. The Gupta wrote it as a curved line, and the Nagarisometimes added a small circle on the left (rotated a quarter turn