90 (number)
90 (ninety) is the natural number preceded by 89 and followed by 91.
| 90 | |
|---|---|
| Cardinal | ninety |
| Ordinal | 90th (ninetieth) |
| Numeral system | 90 |
| Factorization |  |
| Divisors | 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, 90 |
| Roman numeral | XC |
| Binary | 10110102 |
| Octal | 1328 |
| Duodecimal | 7612 |
| Hexadecimal | 5A16 |
Contents |
In mathematics
- Because 90 is the sum of its unitary divisors (excluding itself), it is a unitary perfect number, and because it is equal to the sum of a subset of its divisors, it is a semiperfect number. 90 is a pronic number. But it is also a nontotient. It is a Perrin number, preceded in the sequence by 39, 51, 68.
- In normal space, the interior angles of a square measure 90 degrees each. Also, in a right triangle, the angle opposing the hypotenuse measures 90 degrees, with the other two angles adding up to 90 for a total of 180 degrees.[1] Thus, an angle measuring 90 degrees is called a right angle.[2]
- 90 is divisible by the sum of its base 10 digits, thus it is a Harshad number.
In science
- Ninety is the atomic number of thorium, an actinide. As an atomic weight, 90 identifies an isotope of strontium, a by-product of nuclear reactions including fallout. It contaminates milk.
- The latitude of the North Pole and the South Pole are 90 degrees.
In religion
Ninety of the Psalm are credited to Moses; some credit the ninety-first psalm to him as well.
In sports
- Nike Total 90 Apparel is a brand name of football apparel and football equipment from equipment bags to goalkeeper gloves
- Major League baseball bases are 90 feet (27 m) away in distance
- The car number most associated with former NASCAR team owner Junie Donlavey
- The number of minutes in a football (soccer) match.
In Wellness Plans
- P90X is a rigorous work out plan for 90 days with proclaimed incredible results.