The 25 (number) reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

25 (number)

'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
Hexadecimal	19

In mathematics

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 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.

In base 10, it is easy to test for divisibility by 25, by seeing if the last two digits of the number are 25, 50, 75 or 00. As a consequence of that, it is a 1-automorphic number.

In other fields

Twenty-five is:

• The atomic number of manganese.
• In years of marriage, silver wedding anniversary.
• The minimum age to be elected to the House of Representatives. "Under 25" is a common cut-off for designating youth.
• The number of cents in a quarter, an American coin with George Washington's portrait, and a Canadian coin.
• The designation of United States Interstate 25, a freeway that runs from New Mexico to Wyoming.
• The number of Florida electoral votes for the 2000 U.S. presidential election.
• Historical years: 25 A.D., 25 B.C, or 1925

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