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### Infinity

Mathematics uses the concept of **infinity**. It is written as ∞ for infinitely large and as Δ*x* for infinitely small. But beware, for it are not numbers. You can perform calculations with it. If only you know what you are doing, because there are sometimes really surprises.

##### Infinitely large

We must always take care that ∞ has no fixed value, so

∞ + 1 = ∞

This works the same way for every number, also for very large ones. And even for

∞ + ∞ = ∞

You can perform subtractions

∞ − 1 = ∞

That works for every number, however

##### Infinitely small

We take care, that Δ*x*→0, so

as Δ*x* is neglectable. But here again you see