"He has been taking care of a child since he was eighteen."

Translation: Od osmnácti let se stará o dítě.

[BoneheadBass]

I was wrong on this one, with "Stará se o dítě od svého osmnáctého roku." The translation in my head was "He has been taking care of a child since his eighteenth YEAR," so I used genitive singular. The correct answer offered, however, appears to be genitive plural -- Stará se o dítě od svých osmnácti roků -- and I don't know why. Could someone explain, please?

Meanwhile, since I think I've gotten this one wrong before, I should probably get the answer above (Od osmnácti let se stará o dítě) locked into my head...

= = = = =

UPDATE -- Thanks to both of you for your replies, and for the addition. Eventually, I'll master the right way to talk about age...

[Nemesis_NaR]

To keep it short: "Stará se o dítě od svého osmnáctého roku" is grammatically correct and possible, however, it's not a common way how to speak about age.

[VladaFu]

But it is not unheard of either, adding.

[Milunka96763]

Jak, prosím, přeložit: O dítě se stará od svých osmnácti?