In mathematics books, 3 represents a real number, that is, an integer greater than any natural number less than 3. At the same time, the number 3 is also a prime number because it has only two positive factors, 1 and 3. This property is very important, and many mathematical problems are related to prime numbers.

3 has a wide range of applications in mathematics. For example, in geometry, a triangle is a geometric figure composed of three line segments. In addition, the definitions and properties of trigonometric functions such as sine, cosine and tangent in mathematics are closely related to triangles. In statistics, trinkets and standard deviation both involve 3 in mathematics.

Humans cannot live without numbers. Numbers are an essential element in our life, and as one of them, 3 also has many symbolic meanings in human culture. For example, three digits are usually more difficult to forget and remember than two digits. It is also symbolic in many cultures, such as the Trinity in Christianity and the three cardinals and five licenses in China. So 3 is of historical and cultural significance to human beings.