рубли

In a sentence

• Вчера обмених 200 рубли за долари.

  Yesterday I exchanged 200 rubles for dollars.

  In this sentence, 'рубли' is used as a nominative plural to indicate the specific currency that was exchanged.

• За подаръка похарчих само 50 рубли.

  For the gift, I only spent 50 rubles.

  Here, 'рубли' is used in the accusative plural to denote the amount of money spent.

• На пазара цената беше зададена в рубли.

  At the market, the price was listed in rubles.

  In this example, 'рубли' appears in the prepositional plural case after the preposition 'в', specifying the currency context.