The exclamation mark symbol is used in math to represent the factorial operator. Typically, the symbol is used in an expression like this:
In plain language, this means take the factorial of the number five.
The factorial operator is represented using the exclamation mark. The operator is unary, meaning that it only operates on one expression. The operator is useful when calculating combinations and permutations.
The number of permutations of n distinct items is given by n factorial. A permutation is a unique ordering or arangment of the set of items.