Constant is a fixed value. Is any number except letters, including positive and negative integers and positive and negative decimals, fractions, zeros and irrational numbers (such as π). For example, the ratio of the circumference to the diameter of a circle is π, and the expansion coefficient of iron is 0.0000 12.

Constant is a name with a certain meaning, which is used to replace numbers or strings, and its value never changes. In mathematics, the capital letter "c" is usually used to represent a constant. A mathematical constant refers to a constant with a constant value, and vice versa. Unlike most physical constants, the definition of mathematical constants has nothing to do with all physical measurements.

Number of constant terms

The degree of a single item is the exponential sum of letters, and the constant item has no letters, so the degree is 0. As for the number of constant terms, it can also be understood as follows: match a constant with a letter factor with an index of 0 that is not equal to 0 (nonzero zeroth power is equal to 1). Obviously, the number of constant terms is 0.

Another thing to note is that π and e are not letters, but constant terms. For example, the coefficient of πab is not 1, but π. Because π represents a specific number: 3. 14 15926...π is also a constant term. e = 2.7 1828 1828459。