For example: Z=a+bi, then ReZ=a, imz = b imaginary number imaginary number real number symbols take the first two letters respectively. Rational numbers are produced with people's production practice. The discovery of irrational numbers should be attributed to the Pythagorean school in ancient Greece. The appearance of irrational numbers contradicts democritus's "atomism".

real number

It can be used to measure continuous quantities. Theoretically, any real number can be expressed as an infinite decimal, and to the right of the decimal point is an infinite series (cyclic or acyclic). In practice, real numbers are often approximate to a finite decimal (n digits are reserved after the decimal point, and n is a positive integer). In the computer field, because computers can only store a limited number of decimal places, real numbers are often represented by floating-point numbers.