milljarðar

In a sentence

• Útflutningstekjurnar námu fimm milljörðum íslenskra króna á síðasta ári.

  The export revenues amounted to five billion Icelandic kronas last year.

  In this sentence, 'milljarðar' (billion) is used in the dative plural form as it represents a number related to a quantity, specifically the revenue.

• Það búa rúmlega sjö milljarðar manna á jörðinni.

  There are just over seven billion people living on Earth.

  Here, 'milljarðar' is in the nominative plural form because it refers to the number of people.

• Þeir þurftu að eyða tveimur milljörðum í hönnun verkefnisins.

  They had to spend two billion on the project design.

  In this sentence, 'milljarðar' appears in the dative plural form again because the number expresses an amount being spent.