# What does the ! mean in math formulas?

by Richard
(USA)

##### Question
I was taking an online test and the question was what does 4! mean. Do you know what this means?

It's the factorial sign (!). 4! simply means that we are taking the product of 4×3×2×1. See some examples below:

1! = 1
2! = 2×1 = 2
3! = 3×2×1 = 6
4! = 4×3×2×1 = 24
5! = 5×4×3×2×1 = 120

In general:
n! = n×(n-1)× (n-2)× .... ×3×2×1

That's all.

### Comments for What does the ! mean in math formulas?

Average Rating

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 Sep 06, 2016 Rating Helpful NEW by: Tom felton I needed for my math class

 Aug 25, 2016 Rating Thanks NEW by: Batman Thanks this helped a lot by the way "I'm batsman"

 Jun 01, 2016 Rating What does x! mean??? NEW by: Anonymous I really needed this information for the homework that is due tomorrow. The formula is kind of weird, but my math teacher said it was right. Thanx!!

 May 22, 2016 Rating thx NEW by: Anonymous this really helped me in class

 Apr 13, 2016 Rating COOL! NEW by: Sue Kooky Thanks!I was taking a test and this was on it, now I know what it means!

 Jan 01, 2016 Rating Factorial sign NEW by: Anonymous Fine. The mode of explanation is easily perceptible.

 Dec 19, 2015 Rating ! NEW by: Anonymous Perfect - very clear

 Oct 19, 2015 Rating Thanks NEW by: Anonymous Now I understand way more things in math class!

 Oct 12, 2015 Rating No help by: Anonymous No help at all

 Jun 30, 2015 Rating good by: Anonymous good

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 Dec 08, 2014 Rating Great by: Anonymous Great! Thanks