## ⓘ 1000 (number)

1000 or one thousand is the natural number following 999 and preceding 1001. In most English-speaking countries, it is often written with a comma separating the thousands unit: 1.000.

It may also be described as the short thousand in historical discussion of medieval contexts where it might be confused with the Germanic concept of the "long thousand" 1200.

## 1. Notation

- 1 × 10 3 exactly - in scientific normalized exponential notation ;
- The decimal representation for one thousand is
- 1000 - a one followed by three zeros, in the general notation ;
- 1 E+3 exactly - in scientific E notation.
- 1 × 10 3 - in engineering notation, which for this number coincides with

- The SI prefix for a thousand units is "kilo-", abbreviated to "k" - for instance, a kilometre or "km" is a thousand metres.
- Multiples of thousands are occasionally represented by replacing their last three zeros with the letter "K": for instance, writing "$30K" for $30.000, or denoting the Y2K computer bug of the year 2000.
- A thousand units of currency, especially dollars or pounds, are colloquially called a grand, which can be abbreviated with a "G" suffix.
- In the SI writing style, a non-breaking space can be used as a thousands separator, i.e., to separate the digits of a number at every power of 1 000.

## 2. Properties

- 1000 is a Harshad number in base 10.
- The sum of Eulers totient function over the first 57 integers is 1000.
- Prime Curios! mentions that 1000 is the smallest number that generates three primes in the fastest way possible by concatenation of decremented numbers 1000999, 1000999998997, and 1000999998997996995994993 are prime. The criterion excludes counting the number itself.