Breakdown of Ten błąd kosztował nas piętnaście minut.
ten
this (m)
kosztować
to cost
piętnaście
fifteen
nas
us
Questions & Answers about Ten błąd kosztował nas piętnaście minut.
Why is 'minutes' translated as minut and not minuty?
Because of the number piętnaście (fifteen). In Polish, numbers 5 and above require the noun that follows them to be in the Genitive plural case. The base word is minuta (a feminine noun), and to make it Genitive plural, we drop the final '-a', leaving just minut.
The current lesson says numbers 5 and above make past tense verbs take a neuter singular ending. Why is the verb here kosztował (masculine)?
That rule only applies when the number phrase itself is the subject of the sentence! Here, the subject doing the action is Ten błąd (This mistake), which is a masculine singular noun. The verb agrees with błąd, so it takes the regular masculine singular past tense form kosztował.
What case is the pronoun nas in this sentence?
It is in the Accusative case. The verb kosztować (to cost) requires the Accusative case for the person or people paying the cost. Nas is the Accusative form of my (we).
How would this sentence change if the mistake only cost us two minutes?
Numbers 2, 3, and 4 do not trigger the Genitive plural. Instead, they pair with the standard plural forms. For two minutes, you would use dwie minuty instead of piętnaście minut.