The capital Latin letter Q is used in mathematics to represent the set of natural numbers. Usually, the letter is presented with a “double-struck” typeface when it is used to represent the set of rational numbers.
The set of rational numbers is denoted with the Latin Capital letter Q presented in a double-struck type face.
The latin letter q.
The set of natural numbers, also called the counting numbers, contains the numbers 0, 1, 2, 3, ...