The value of roubles can differ between Russia and Belarus, impacting purchasing power. What costs 100 Russian roubles might be more or less in Belarussian roubles.
Pro Tip 2/3
Not Universal
The rouble is not widely accepted outside its home countries, unlike the dollar or euro. You can't use roubles to buy souvenirs in Paris.
Pro Tip 3/3
Economic Indicator
The strength of the rouble can reflect Russia's and Belarus's economic situations. When oil prices are high, the rouble usually strengthens.