Real number that has special significance in certain areas of mathematics and to which tradition has assigned a specific name.

These real numbers known as constants correspond to results obtained through algebraic calculations and deductions. They play a very important role in various mathematical theories in geometry, arithmetic, algebra, probabilities, calculus, etc.

### Examples

The number *π* which represents the ratio of a circle’s circumference to its diameter, has an approximate value of 3.141 592.

The real number written as *e* whose approximate value is 2.718 281 8 is the base of natural or Napierian logarithms.

The golden ratio, usually represented by the Greek letter φ, is also a mathematical constant whose approximate value is 1.618.