A set is a collection of numbers (or objects).

A set is usually symbolized by an uppercase letter (for example "S").

Each number (or object) in a set is called a member or element of the set.

If S represents a set, then n(S) represents the number of elements in set S.

A set is usually illustrated in a Venn diagram by a circle or rectangle (but almost any shape can be used).

Members of the set are placed inside the circle (or rectangle).

Members not in the set are placed outside of the circle (or rectangle).

If a number or object (a) is a member of a set (S) we write "a S" which means "a is an element of S".

If a number or object (b) is NOT a member of a set (S) we write "b S" which means "b is not an element of S".

A: {0, 1, 2, 3}

B: {10, 20, 30, 40, ...}

C: {0}

D: {}

I: {..., -3, -2, -1, 0, 1, 2, 3, ...} (The integers)

n(A) = 4.

n(B) = ∞

n(C) = 1.

n(D) = 0.

n(I) = ∞

S: The possibilities that can occur when tossing a die.

S: {1, 2, 3, 4, 5, 6}

n(S) = 6.

Subset of a set

Proper subset of a set

Complement of a set

Union of sets

Intersection of sets

Venn Diagram of sets