Person who can tell me all this shiz..

I want to know how many 2 object combinations you can make with different things. Order does matter, but no doubles.
Example:
a b c
ab
ac
ba
bc
ca
cb

Will you do it with..
27..
14..
12..
9..
7..
6..


I need to wrap up the rest of something, and don't feel like doing this soo, yeah.