This is called a "factorial"......it is the procuct of all the positive integers up to, and including, "n"
For example..... n! .... where n = 3....we have 1 x 2 x 3 = 6
Or ..... n! .... where n = 4 = 1 x 2 x 3 x 4 = 24
This concept is very useful in statistics and probabilty in "counting" operations
BTW .... 0! is defined to be = 1
