Questions & Answers about To jest trzynasty slajd naszej prezentacji.
Why use trzynasty instead of trzynaście?
Trzynaście is the cardinal number ("thirteen"). Here, you need the ordinal number ("thirteenth") to say which slide it is. Ordinal numbers in Polish behave exactly like adjectives, so trzynasty takes a masculine singular nominative ending to agree with the masculine noun slajd.
Does trzynasty have anything to do with the fractions we are learning in this lesson?
Yes! Fractions in Polish use ordinal numbers for the bottom number. While here trzynasty is just a regular adjective describing a masculine noun, if you wanted to build the fraction "one thirteenth", you would use the feminine version of this exact word: jedna trzynasta.
Why is the ending of prezentacja changed to prezentacji?
It is in the genitive case, which is used here to mean "of" (the slide of our presentation). For feminine nouns ending in -cja, the genitive ending is always -cji. The pronoun nasza (our) also changes to its feminine genitive form, naszej.
I learned that jest usually requires the instrumental case. Why is trzynasty slajd in the nominative?