The set of complex numbers extends the set of real numbers and is defined in the form of , where represents the square root of negative one and and are members of the set of real numbers. The set is denoted using the latin capital letter presented in a double-struck typeface as the symbol .

The set of natural numbers, denoted as ℕ, includes all positive integers starting from 0. In some definitions, it also starts at 1 instead of zero.

The set of integers, denoted as ℤ, includes all positive and negative whole numbers, along with zero. For example, the numbers -2, 0 and 3 are all integers, but numbers like 1/2 or the square root of 2 are not.

The set of rational numbers can be defined by the quotient of two numbers belonging to the set of integers, where the divisor is non-zero.

The set of real numbers includes all rational and irrational numbers. It represents the entire continuum of possible number values from negative infinity to positive infinity.