This is strange!
What is an expanded Universe? It is a Universe where you can talk about a negative, and complex number of things. Physical things are also multiplicative, and additive. Let us delve into the weirdness of the Expanded Universe.
Negative and complex numbers
Let us say you have two apples, and you take away three apples. What do you get? In our Universe, this doesn't make sense. In the Expanded Universe, you get one anti-apple. This could be expressed with this equation: 2 - 3 = -(1). If you added an anti-apple to your collection of apples, one apple would disappear. This is true magic!
For complex numbers, you need an apple that is a whole new type of apple. We will use fake apples for imaginary numbers. For a complex number of apples, we make a set of how many real apples there are, and how many fake apples there are.
We get for free that there are anti-fake apples.
To multiply apples, we multiply the number of apples that there are. In the real world, this would not make any sense, but this is our Universe. We are coming up with the rules on how it behaves, and it may be different to how our Universe behaves. So this would be valid in Mathematicsland.