We were travelling in Europe, which was fun, plus all the prices for things are in made-up numbers! So in Norway I bought gas for something like 15 kroner a liter, which was made all the easier by the fact I wasn't doing the conversion in my head.
The reason I wasn't doing the conversion is that I knew that was about US$6.20 a gallon or -- more frighteningly for me, since I spend Canadian dollars -- CDN$9.00 a gallon.