25

25 is a natural number following 24 and preceding 26. It is a square number, being 5^2 = 5 × 5. It is the smallest square that is also a sum of two (non-zero) squares: 25 = 3^2 + 4^2. Hence it often appears in illustrations of the Pythagorean theorem.

Mathematics

In mathematics, 25 is a square number, made up from the product of a single integer (5) with itself. This makes it a special case in several mathematical equations. It is also a Cullen number, as 25 is of the form 2^n - n - 1.

25 is the sum of the single-digit numbers 2 and 5, and its "25" digit sequence is the first to repeat in an infinite decimal, for example in 1/25 = 0.04.

Science

In science, 25 is the atomic number of manganese. In astronomy, Messier object M25 is a magnitude 6.5 open cluster in the constellation Sagittarius.

Culture

In culture, the number 25 is often used to mark significant anniversaries. These are often referred to as 'silver' anniversaries, particularly in the context of marriage.

Sports

In sports, 25 is often used as a jersey number in football, basketball, and other team sports. Notable athletes who have worn this number include American football player Richard Sherman and baseball player Mark McGwire.

See also

• Square number
• Pythagorean theorem
• Manganese
• M25 (Messier object)

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