Russian counts in three patterns. One takes the nominative singular: один номер. Two, three and four take the genitive singular: два номера. Five and above take the genitive plural: пять номеров. Numbers ending in those digits follow the same rule, except the teens.
Examples
- Я хотел бы забронировать один номер.
- I would like to book one room.
- Мы остаёмся на три ночи.
- We are staying for three nights.
- В гостинице пять номеров с видом.
- The hotel has five rooms with a view.
The mistake to avoid
The teens all take the genitive plural: двенадцать номеров.
Where this fits in
Travel & directions, Russian A2: Get around in a Russian-speaking city: take transport, ask the way, check into a hotel, and buy a ticket.