Some people have no difficulty mentally calculating the equivalent of pesos or yen or euros in dollars – on the spot, the seller of the English teapot or Turkish prayer rug or Mexican candlestick impatiently waiting. Then there are the rest of us. There are devices and dodads to do the chore, but they take almost as long as pencil and paper.

So try this: Go to www.oanda.com. Click “Travelers” at the top of the page. After the jump, scroll down in the “Leisure Traveler” column and click “Travelers Currency Cheatsheet”. Insert the foreign currency for which you wish to exchange your dollars. The program will then produce a chart listing stepped amounts of dollars to, say, euros. Another chart will reverse the equation, say euros to dollars. They are conveniently wallet-sized.

Print out the charts, cut them out, and take them to the nearest UPS or stationery store to be laminated. They’ll cost about a buck.