"Дев'ятнадцять машин"

Translation: Nineteen cars

[TheRealCardoso]

Why can't it be 3 cars?

[Andrusxot]

Because машин is the genitive plural. When the number for a noun is larger than 5 the noun takes the genitive plural. Three cars would be = "Три машини." When the number is less than 5. It takes the nominative plural, basically the normal plural of the word.

[Lobel123]

Thank you very much!

[Rachelb0728]

Thank you! I've been trying to figure that out every time!

[PonyDesu]

Because дев'ятнадцять means 19.

[Warao1]

Is машин also masculine? Is машини also accusative plural as well as nominative?
Are студенти/студентки accusative plurals?

[artyom.yakovenko]

Машина is feminine. Машини can be both plural in Nominative and Accusative, as well as singular in Genitive.

Студенти & студентки are Nominative plurals. The Accusative plurals would be студентів & студенток respectively.

Actually студентки can be also Genitive singular, for example:

<pre>Who did you hear it from? - Від кого ти це почув? I heard it from a (female) student. - Я почув це від студентки. </pre>