"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?

[Juggler69]

What's wrong with:
Od osmnácti let se o dítě stará.

[VladaFu]

That is very strange. It means wasn't taking care of the child before and we think he probably should have, he was probably neglecting it. You are stressing the verb too much in the final position.