Breakdown of Wir merken den Fehler sofort.
wir
we
sofort
immediately
den
the; (masculine, accusative)
der Fehler
the mistake
Questions & Answers about Wir merken den Fehler sofort.
Why is it den Fehler and not der Fehler?
Because den is the accusative singular article for masculine nouns. Fehler is masculine (der Fehler in the nominative), but as the direct object of merken it takes accusative: den Fehler. Masculine: nominative der → accusative den.
Does merken take the accusative or dative?
In the sense of “notice,” merken is a transitive verb that takes a direct object in the accusative: etwas merken (Akk.). The dative shows up only in the separate reflexive construction sich (Dat.) etwas merken (“to memorize/remember something”).
Can I say Wir merken uns den Fehler sofort? How does that change the meaning?
Yes, but it means something different: Wir merken uns den Fehler sofort = “We commit the mistake to memory right away.” Without uns, Wir merken den Fehler sofort means “We notice the mistake right away.”
Where should sofort go? Is Wir merken sofort den Fehler also correct?