Mulling mathematics on Monday

After telling you NINE is my favorite number, look what I found — a clock whose only numbers are 9s.  Thanks to my Facebook friend Jean, who shared it with friends.  Now I want a mathematician to explain to me the equation in 5th place with an exclamation mark following the square root of 9.  That never came up in my math classes.  All I've found by googling is that the exclamation mark is the "factorial operator."  I can see that it doubles the square root of 9, but how does it work?  Okay, I revised my question and got an answer:

Q:  What does a factorial operator do in math?

A:  Factorial, in mathematics, is the product of all positive integers less than or equal to a given positive integer and denoted by that integer and an exclamation point. Thus, factorial seven is written 7!, meaning 1 × 2 × 3 × 4 × 5 × 6 × 7.

So the square root of 9 equals 3.  The factorial of 3 means 1 × 2 × 3 = 6.  And 9 over 9 = 1.  So 6 - 1 = 5.  Yay, I got it!  The other numbers are pretty simple.