Learn Finnish: Minä totun uuteen arkeen nopeasti. - I am getting used to the new everyday life quickly.

The verb tottua (to get used to) is a high-frequency verb that requires the illative case. While in English you get used to something, in Finnish you get used into something. Because of this rection rule, both the noun arki and its adjective uusi must take the illative endings.

How does the word arki (everyday life) turn into arkeen?

The word arki is an older Finnish word ending in -i. For many of these words, the -i changes to an -e- when you add an ending, making the stem arke-. To form the illative case, you double the last vowel of the stem and add -n, which gives us arkeen.

Why is the word for new written as uuteen instead of just uusi?

In Finnish, adjectives have to match the noun they describe. Since the verb tottua forces the noun into the illative case (arkeen), the adjective uusi (new) must also change into the illative case. The stem of uusi is uute-, so doubling the vowel and adding -n makes it uuteen.

How is the word nopeasti (quickly) formed?