Number Combinations

Here is what my table kind of looks like

A B
4 0.25
7 0.3
2 0.1
3 0.15


4 0.30
1 0.4
8 0.05
2 0.1

Now there is the number and the number(A) that it value it represents (B). This is what I want. I want to see all possible number combinations between the upper and lower A columns listed veritcally under the whole set, with out duplicating any numbers and with the upper numbers only being in the 1st position and the lower numbers being in the second position Ex( 4-1, 4-8, 4-2, 7-4, 7-1, ect, ect (listed vertically). Now in column B under, right beside each possible combination I want to see the result of the two values multiplied (ex. beside 4-1 I would like to see 0.1)

So below that mess listed above I want to see something like this

A B
4-1 0.1
4-8 0.0125
ect
ect
ect

I want to be able to swith the values around and have it automatically make the correction.