FACTOID # 10: The total number of state executions in 2005 was 60: 19 in Texas and 41 elsewhere. The racial split was 19 Black and 41 White.

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Encyclopedia > Number 25

25 (twenty-five) is the natural number following 24 and preceding 26.

 List of numbers — Integers << 20 21 22 23 24 25 26 27 28 29 >>
Cardinal twenty-five
Ordinal twenty-fifth
Factorization
Roman numeral XXV
Binary 11001

It is a square number, being 52 = 5 × 5, and it is also the sum of two squares, 32 + 42, often used in demonstrations of the Pythagorean theorem. It is the smallest square that's also a sum of two squares. 25 is a centered octagonal number and an automorphic number.

It is also a Cullen number. 25 is the smallest pseudoprime satisfying the congruence 7n = 7 mod n. It is also a Somer pseudoprime based on 6.

Within base 10 one can readily test for divisibility by 25 by seeing if the last two digits of the number match 25, 50, 75 or 00.

## In science

In astronomy,

Messier object M25, a magnitude 4.9 open cluster in the constellation Sagittarius
The New General Catalogue object (http://www.ngcic.org/) NGC 25, a magnitude 11.9 barred spiral galaxy in the constellation Phoenix
The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) of the solar eclipse series which began on -2051 April 19 and ended on -771 May 26. The duration of Saros series 25 was 1280.1 years, and it contained 72 solar eclipses.
The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on -2038 August 6 and ended on -469 March 5. The duration of Saros series 25 was 1568.6 years, and it contained 88 lunar eclipses.

## In other fields

Twenty-five is:

Results from FactBites:

 Laboratory Primate Newsletter Volume 25 Number 3 (10588 words) The number of neuroscience studies of primates dropped only slightly over the 12-year period, from about 11% in 1973 to 8% by 1985. Bowden says that "from the late 1960's to the present the number of primates imported from the wild has dropped by about 90%." Overall, monkeys are used much less in research, and the development of alternative animal models and in vitro systems for much drug and toxicity testing are significant factors. The number of parasites in this animal was considered significant and contributed to the death of the animal.
More results at FactBites »

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