| ||||
---|---|---|---|---|
Cardinal | one | |||
Ordinal | 1st (first) | |||
Numeral system | unary | |||
Factorization | 1 | |||
Divisors | 1 | |||
Greek numeral | Α´ | |||
Roman numeral | I | |||
Roman numeral (unicode) | Ⅰ, ⅰ | |||
Greek prefix | mono- /haplo- | |||
Latin prefix | uni- | |||
Binary | 12 | |||
Ternary | 13 | |||
Quaternary | 14 | |||
Quinary | 15 | |||
Senary | 16 | |||
Octal | 18 | |||
Duodecimal | 112 | |||
Hexadecimal | 116 | |||
Vigesimal | 120 | |||
Base 36 | 136 | |||
Greek numeral | α' | |||
Persian | ١ - یک | |||
Arabic | ١ | |||
Urdu | ||||
Ge'ez | ፩ | |||
Bengali & Assamese | ১ | |||
Chinese numeral | 一,弌,壹 | |||
Korean | 일, 하나 | |||
Devanāgarī | १ | |||
Telugu | ೧ | |||
Tamil | ௧ | |||
Kannada | ೧ | |||
Hebrew | א (alef) | |||
Khmer | ១ | |||
Thai | ๑ | |||
Malayalam | ൧ | |||
Counting rod | 𝍠 |
1 (One) is the first natural number, followed by two. The Roman numeral for one is I.
In mathematics, 1 is the multiplicative identity. It is sometimes called the "unity".[1] It is also the only number for which these special facts are true:
In mathematics, 0.999... is a repeating decimal that is equal to 1. Many proofs have been made to show this is correct.[2][3]
The number one is important for computer science, because the binary numeral system uses only 1s and 0s to represent numbers. In machine code and many programming languages, one means "true" (or "yes") and zero means "false" (or "no").