The number 4 is a natural number that follows 3 and precedes 5. It is a square number (2²=4), the smallest semiprime and composite number, and holds significance in various fields such as mathematics, culture, and technology
Mathematical Properties of 4
- It is the smallest semiprime and composite number.
- There are four elementary arithmetic operations: addition, subtraction, multiplication, and division.
- The four-color theorem states that any planar map can be colored with four colors such that no adjacent regions share the same color.
- A four-sided plane figure is called a quadrilateral or tetragon.
- The tetrahedron is a solid figure with four faces and four vertices, the simplest Platonic solid.
- The smallest non-cyclic group has four elements, known as the Klein four-group
Cultural and Symbolic Significance
- In many East Asian cultures, the number 4 is considered unlucky because it sounds like the word for "death" in Chinese, Korean, and Japanese.
- The number four has been used symbolically to represent wholeness and universality, linked to the cross and the square.
- It is sacred to the Zia tribe in New Mexico.
- The number four appears in logic and philosophy, such as the Square of Opposition, which consists of four forms of categorical propositions
Other Facts
- In internet slang, "4" can substitute for the word "for."
- The digit 4 has evolved from Brahmic numerals and has different typographical forms, including an open-top variation used in digital displays and some fonts
- The year 4 AD was notable historically for events in the Roman Empire and other regions
In summary, 4 is a fundamental number with rich mathematical properties and cultural meanings worldwide
