∀ - Universal quantifier (for all)
∃ - Existential quantifier (there exists)
→ - Implication (implies)
¬ - Negation (not)
∨ - Disjunction (or)
∧ - Conjunction (and)
∅ - Empty Set
Ν - The set of natural numbers
Ζ - The set of integers
∩ - Intersection
∪ - Union
− - Set difference
⊑ - is a subset of
⊏ - Is a proper subset of
∈ - Is a member of
∉ - is not a member of
∈ - means is an element of. for example 3 ∈{1,2,3,4,5}.
⊃ - A ⊇ B means every element of B is also an element of A. A ⊃ B means A ⊇ B but A ≠ B.
⊂ - (subset) A ⊆ B means every element of A is also an element of B.(proper subset) A ⊂ B means A ⊆ B but A ≠ B.
Ⅾ - Domain
I - assignment
-> - maps to
Definition
The definition of the factorial is that for any positive whole number n, the factorial:
n! = n x (n -1) x (n - 2) x . . . x 2 x 1
Examples for Small Values
1! = 1
2! = 2 x 1 = 2
3! = 3 x 2 x 1 = 6
4! = 4 x 3 x 2 x 1 = 24
5! = 5 x 4 x 3 x 2 x 1 = 120
6! = 6 x 5 x 4 x 3 x 2 x 1 = 720
7! = 7 x 6 x 5 x 4 x 3 x 2 x 1 = 5040
8! = 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 40320
9! = 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 362880
10! = 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 3628800