In mathematics, n is the abbreviation of $ number, which means quantity. The Chinese meaning can be understood as "several", which is a numeral and has no unit of measurement.

For example, a natural number refers to the number or quantity of natural attributes.

Real number: real number

imaginary number

Rational number: rational number

In the mathematics you are studying now, n means uncertainty and number. He can represent any number. Because he means quantity, in many cases, he means natural number.

In addition, capitalized n and lowercase n have different meanings.

Capitalized n often has practical referential meaning, and lowercase n mostly represents numbers. For example, n means n people.