In maths, ! represents the factorial of a number. The factorial applies to all natural numbers, except zero. To calculate the factorial of a number, multiply the number chosen by the number that is one lesser than it, and then multiply the result by the number 2 times lesser than the original number, etc. like this:
$ 7! = 7 * 6 * 5 * 4 * 3 * 2 * 1 $
Thus, 7! would be 5040.
Work out the following:
The answers are here: Factorial of a number/answers