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?
Answer
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?

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Jun 01, 2016
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
thx NEW
by: Anonymous

this really helped me in class

Apr 13, 2016
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
Factorial sign NEW
by: Anonymous

Fine. The mode of explanation is easily perceptible.

Dec 19, 2015
! NEW
by: Anonymous

Perfect - very clear

Oct 19, 2015
Thanks NEW
by: Anonymous

Now I understand way more things in math class!

Oct 12, 2015
No help
by: Anonymous

No help at all

Jun 30, 2015
good
by: Anonymous

good

Jun 03, 2015
Thanks!
by: Ellen Moore

Nice post!

May 10, 2015
Great Stuff
by: Anonymous

Its a great stuff and must be appreciated anyway.

Jan 14, 2015
2015 is now
by: Anonymous

thx, that was helpful

Dec 08, 2014
Great
by: Anonymous

Great! Thanks

Oct 10, 2009
helpful
by: Anonymous

very helpful. Thanks!

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