# Factorial Question

1. Nov 30, 2006

### TheRobsterUK

Hi,

I have a question about factorials that I'm hoping someone can help me with.

I know that the factorial n! means the product of the integers from 1 to n, for example if I have 4! then this is equal to 4 x 3 x 2 x 1 = 24, but I have an equation which contains the term:

k(n-1)!

I am not sure how to interpret this...for instance, if we assume that k=4 and n=8, does this give:

4(8-1)!
= 4 x 7!
= 4 x 5,040
= 20,160

Or does it give:

4(8-1)!
=4 x 7!
=28!
=3.0489 x 10^29

I'm guessing it's the first one but am not sure...can someone confirm or provide the correct answer please?

Many Thanks
-Rob

2. Nov 30, 2006

### arildno

Note that the notations:
(k(n-1))!, k((n-1)!) CANNOT be misunderstood.

The convention used, in order to save parentheses is:
k(n-1)!=k((n-1)!).

Note that this convention is akin to the one used with expressions involving a power:
$$A*B^{n}=A*(B^{n})$$
rather than [itex](A*B)^{n}[/tex]

Last edited: Nov 30, 2006