Numbers 1 to 4 in the dative (einum, tveimur)

In Icelandic, the numbers 1 through 4 change their form depending on the case and gender of the noun they modify. In this lesson, the dative is triggered in two main ways:

  • Verbs: Certain verbs govern the dative case, including svara (to answer), skila (to return), eyða (to spend [time]), and ljúka (to finish).
  • Prepositions: When describing time intervals or durations, the prepositions í (in) and á (on/in) take the dative case.

The Number 1 in the Dative

The number one (einn) matches the gender of the singular noun it modifies. Its dative forms are:

  • Masculine: einum
  • Feminine: einni
  • Neuter: einu
She spends one month in Iceland.
Hún eyðir einum mánuði á Íslandi.
They finish the project in one night.
Þær ljúka verkefninu á einni nóttu.
Doesn't he answer one child?
Svarar hann ekki einu barni?

The Numbers 2, 3, and 4 in the Dative

The numbers 2, 3, and 4 use a single dative form for all three genders:

  • Two: tveimur
  • Three: þremur
  • Four: fjórum

Notice that they all end in -um. This is the exact same ending you will often see on the dative plural nouns they modify (like köflum, dögum, and börnum).

We finish two chapters today.
Við ljúkum tveimur köflum í dag.
The book is in three chapters.
Bókin er í þremur köflum.
The car stops in four seconds.
Bíllinn stoppar á fjórum sekúndum.
Where do you spend three days?
Hvar eyðir þú þremur dögum?
We finish the project in four steps.
Við klárum verkefnið í fjórum skrefum.