Constant

In math, a constant is a special value that doesn’t change. The symbol is often used in an expression to indicate a generic unchanging value. There are also some math constants that mathematicians have given their own symbol

mathematicians have

a significant value that mathematicians have assigned a symbol representation.

Tau
Tau

The circle constant τ (tau) is a geometric constant approximately equal to 6.283. The numeric value is defined as the length of any circle's circumference divided by the length of its radius.

Pi
Pi

The greek letter π (pi) is a geometric constant approximately equal to 3.1416. Its value is equal to the length of any circle's circumference divided by its diameter.

Euler's Number

Euler's number is a naturally occurring number related to exponential growth and exponential decay. It is also shorthand for the exponential function.

Golden Ratio

The golden ratio is a number represented by the greek letter ϕ (phi). The value of ϕ is approximately 1.618 and is a naturally occurring number in nature.

i
i

The letter "i" is used in mathematics to represent the square root of negative one. The letter is also used to denote the complex part of a complex number.