999 (number)

999 (nine hundred ninety-nine) is the natural number after 998 and before 1000. It is the biggest 3-digit integer.

In mathematics

999 is a palindrome number that is a repdigit. It is also a Kaprekar number and a 3-Kaprekar number, a Harshad number, a trimorphic number, and the smallest result of three 3-digit prime numbers taken from a zeroless pandigital number (149 + 263 + 587 = 999). 999 can be written as the sum of three consecutive cuban primes which is 271 + 331 + 397.

999 can be used in division to make 3-digit decimal recurrences. For example, 123 / 999 = 0.123123123... .

The radical circle of the mixtilinear incircles has a center with trilinear center function

${\displaystyle a{\scriptstyle 999}=\cos A-2,}$

and 999 shows as the Kimberling center ${\displaystyle X{\scriptstyle 999}}$, which is the center of the radical circle.

The largest 1000 digit palindromic prime has a total of 999 digits.

(68 * 10⁹⁹⁹ + 7)/3 and 10⁹⁹⁹ + 7 is prime.

In other fields

• "999: Nine Hours, Nine Persons, Nine Doors" is a Japanese visual novel and adventure game made by Chunsoft.
• 999 is a emergency telephone number in a lot of countries like Bahrain, Bangladesh, Botswana, the Cook Islands, Eswatini, Ghana, Guernsey, Hong Kong, the Republic of Ireland, the Isle of Man, Jersey, Kenya, Macau, Malaysia, Mauritius, Niue, Poland, Qatar, Sudan, Saudi Arabia, Singapore, Trinidad and Tobago, Seychelles, Uganda,\ the United Arab Emirates, the United Kingdom, and Zimbabwe.
• In a lot video games, 999 is the maximum score it could display.

References