- #1
zeion
- 466
- 1
Homework Statement
Why?
Homework Equations
The Attempt at a Solution
I know that n! = n(n-1)...1
and if n = 3 then the possibility for the first entry is 1 or 2 or 3, and if the first entry is 1 then the second cannot be 1 so the second entry has 2 possibilities. But why do I multiply