The set of complex numbers is represented by the Latin capital letter C presented with a double-struck font face. The set of complex numbers extends the set real numbers and is visualized in the complex plane. Typically, the symbol appears in an expression like this:
In plain language, this expression means the variable represents a number in the set of complex numbers.
The Latin capital letter C is used in mathematics as a variable. For example, it appears in geometric formulas as a variable representing the circumference of a circle. It also is used to represent the set of complex numbers, although this is usually indicated with a "double-struck" typeface.
Set of natural numbers.
Set of integers symbol.
The set of rational numbers is denoted with the Latin Capital letter Q presented in a double-struck type face.
The set of real numbers symbol is a Latin capital R presented in double-struck typeface.
A complex number is an extension of the real number line where in addition to the "real" part of the number there is a complex part of the number. The properties of complex numbers are useful in applied physics as they elegantly describe rotation.
The set of complex numbers contains all possible complex numbers. Each complex number has a real part and an complex part.