Right, my maths is terrible, but I'm not even sure this is maths.

I'm gonna order a pizza, I'm in the house, I've got a tenner handy and can't be arsed to go out.

Now this place is buy one get one free on all pizzas delivered, and the other day me and my mate got a 15" pizza each - i was absolutely stuffed with two slices left, and that was conveniently next morning's breakfast.

Now clearly I don't want to get two 15" pizzas this time, that would be stoopid.

So I was going to go for two 9" pizzas. Now common sense tells me that this SHOULD be equivalent to one 18" pizza, giving me more than enough, but 9"s in a pizza sense just seems so small!

Basically the question is, will two 9" pizzas be enough for me now and breakfast tomorrow, bearing in mind what I have just said, or should I fork out an extra £2 for two 12" pizzas, giving me an extra 6"s of pizza?

Thanks for your help in advance.