The number 1000 (one thousand) is a natural number following 999 and preceding 1001. It is commonly written as 1,000 in the short scale and is the cube of ten: 103. The word "thousand" appears in many languages and is a frequent round unit in counting, finance, population figures, and measurement.
Mathematical characteristics
As an integer, 1000 is composite. Its prime factorization is 2^3 × 5^3, so it has 16 positive divisors. The sum of all divisors is 2340, making the sum of proper divisors 1340, which classifies 1000 as an abundant number. In other numeral bases it is represented as binary 1111101000, hexadecimal 3E8, and octal 1750. In Roman numerals it is written as M.
Notation and prefixes
The SI prefix for 10^3 is "kilo-" (symbol k), so a kilometre is 1000 metres. In everyday financial shorthand, a lower-case k or the slang "grand" signal thousands (for example $5k or "5 grand"). In computing there is a historical ambiguity: "kilo" sometimes denotes 1024 (2^10) rather than 1000, so terms like kilobyte may be contrasted with kibibyte.
Common uses and conventions
- Counting and statistics: populations, salaries, and item quantities are often rounded to the nearest thousand.
- Formatting numbers: many locales use a comma, space, or period as a thousands separator to group digits (e.g., 1,000 or 1 000).
- Currency and pricing often use "k" or "K" to mean thousand units.
For further concise numerical context see basic number sequences. For definitions related to groupings and prefixes consult metric prefixes. For numeral-system conversions and representations see positional notations. For historical and linguistic notes on the term and its usages, see word history resources.