Solve this if you are a genius

This “solve this” quiz showed up on my Facebook news feed.

8 = 56
7 = 42
6 = 30
5 = 20
3 = ?

The pattern looks pretty easy, right?

8 × 7 = 56
7 × 6 = 42
6 × 5 = 30
5 × 4 = 20

So what is the correct answer?

Here’s mine:

3 = 3 — even if it’s preceded by a bunch of false statements.

Do you agree?

Update. This is an old post and I thought it had seen all the life it was going to see. Then Angel comes and leaves a comment:

It turns out that the ‘?’ can be whatever we want it to be!

Angel backs up his claim with math. I think we have the definitive answer.