Constant:

For example, the ratio of the circumference to the diameter of a circle, the expansion coefficient of iron is 0.0000 12, which can be said to be constant. 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.

Constants have many meanings:

Specified quantity and number. Some repetitive pattern. A certain or usual number. A certain order. Mathematical terms. A fixed value. Physical terms. In physics, many measured values are called constants. For example, the coefficient of universal gravitation and the acceleration of surface gravity.

The difference between constant and real number:

A constant is a definite number in an equality or inequality. It can be a number or a letter, but it is absolutely unchanged and does not change with other values. Real numbers refer to all numbers that can be represented on the exponential axis, that is, the sum of rational numbers and irrational numbers, excluding imaginary numbers. In other words, a constant is a definite number and a real number is a set.

The mysterious constant π;

Pi π ≈ 3.141465438.86 No matter how big a circle is, the ratio of its circumference to its diameter is always a fixed number. Let's just call this number pi, which is expressed by the Greek letter π. People have long recognized the existence of pi, and the study of pi can even be traced back to BC; Since then, human exploration of pi has never stopped.

Thousands of years have passed, and people have learned more and more about pi, but they have been puzzled by the question of whether pi is reasonable or not. It was not until 176 1 that the German mathematician Lambert proved that π was an irrational number.

π is one of the most basic, important and magical constants in mathematics, which often appears in some occasions unrelated to geometry. For example, if two positive integers are arbitrarily taken out, the probability that they are coprime (the greatest common divisor is 1) is 6/π 2.