$1\text{ nm}$ is equivalent to:

We know the metric values of these units of length:
* $1\text{ nm}=10^{-9}\text{ m}$
* $1\text{ A˚(Angstrom)}=10^{-10}\text{ m}$

Dividing the two values:

$$\frac{1\text{ nm}}{1\text{ A˚}}=\frac{10^{-9}\text{ m}}{10^{-10}\text{ m}}=10$$

$$1\text{ nm}=10\text{ A˚}$$