Some Important Sets of Real Numbers

We list some other important examples of sets of real numbers.

1. The empty set , which has no elements.
2. The finite set {a₁ ,..., a_n}, whose only elements are the numbers a₁, a₂,..., a_n.
3. The set of all x such that x ≠ 0.
4. The set N = {1, 2, 3, 4,...} of all positive integers.
5. The set Z = {...,-3, -2, -1, 0, 1, 2, 3,...} of all integers.
6. The set Q of all rational numbers. A rational number is a quotient m/n where m and n are integers and n ≠ 0.