What is the best currency to take to Russia?

Related questions

1. What's the best time to go to Russia?
2. How cold is Russia in December?
3. Is Scotland colder than England?
4. Is it cold in Russia in the summer?
5. What is the best time to visit Moscow?
6. Can you drink boiled tap water in Moscow?
7. Do they speak English in Moscow?
8. Which is the best month to visit Russia?
9. Can you drink tap water in Russia?
10. What's the coldest city in Russia?

Tags

1. #outside
2. #russia
3. #either
4. #ruble
5. #currency
6. #dollar
7. #which