Ninety
From Wikipedia, the free encyclopedia.

90 (ninety) is the natural number preceded by eighty-nine and followed by ninety-one.

90
Cardinal	ninety
Ordinal	ninetieth
Numeral system
Factorization
Roman numeral	XC
Binary	1011010
Hexadecimal	5A

Mathematics

It is the sums of the squares of the integers 2 to 6, as well as a composite number, with its divisors being 1, 2, 3, 5, 6, 9, 15, 18, 30 and 45, and its factorization is

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.

Other fields

Ninety is:

• The atomic number of thorium, an actinide.
• The designation of American Interstate 90, a freeway that runs from Washington to Massachusetts.
• The code for international direct dial phone calls to Turkey.
• The year AD 90.

89 and 91

The original article can be found at: http://en.wikipedia.org/wiki/Ninety.
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