If you are thinking of representing them as floating point numbers, in general it will not be possible to represent the exact value, but you can represent it to arbitrary precision. For example, when creating your number field you can pick an embedding into CC like so:

```
sage: K.<a> = NumberField(x^3 - 2, embedding=1.2)
sage: CC(a)
1.25992104989487
```

This gives you 53-bit of floating point precision. For more precision, you can use a a field with more precision:

```
sage: CC100 = ComplexField(100)
sage: CC100(a)
1.2599210498948731647672106073
```

Instead of fixing one embedding upon creating your number field, you can also compute all the embeddings into a given field L with `K.embeddings(L)`

, and use one of them explicitly.

The field `QQbar`

represents the algebraic closure of the rationals and allows you to do exact arithmetic with arbitrary algebraic numbers. Depending on what you want to do this may also be suitable for you.