4

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4 is a number, numeral, and digit. It is the natural number following 3 and preceding 5. It is the smallest composite number, its proper divisors being 1 and 2.

Mathematics

In mathematics, the number 4 is significant in various ways:

• It is the smallest composite number.
• It is the smallest square number (2^2).
• It is the only number with the same number of letters as its value in the English language.
• It is the second Fermat prime.
• It is the second square number.

Properties

• 4 is the smallest number of sides of a polygon (a quadrilateral).
• It is the smallest number of vertices of a polyhedron (a tetrahedron).
• It is the smallest number of dimensions of a hypercube.

Science

In science, the number 4 has various applications:

• There are four fundamental forces in physics: gravitational force, electromagnetic force, strong nuclear force, and weak nuclear force.
• There are four nucleotide bases in DNA: adenine, cytosine, guanine, and thymine.

Culture

In various cultures, the number 4 holds different significances:

• In Chinese culture, the number 4 is considered unlucky because it sounds like the word for "death" (死, pinyin: sǐ).
• In Western culture, the number 4 is often associated with stability and order, as seen in the four seasons, four cardinal directions, and four elements (earth, water, air, fire).

Religion

• In Christianity, there are four Gospels: Matthew, Mark, Luke, and John.
• In Hinduism, there are four Vedas: Rigveda, Samaveda, Yajurveda, and Atharvaveda.

Related Pages

• Number
• Mathematics
• Science
• Culture
• Religion