Back in the old days, I used to carry around my phone with a calculator feature to allow me to figure out how cheap the pair of Nikes were. These days, you could still do the same but why not use a currency converter via the web or a smartphone. The advantages are near real-time updates on currency fluctuations and around 180 currencies to choose from.
I have been using XE Currency Converter for ages via the webpage and like all other companies worth their salt, they have an app as well. I tried a few apps from the iTunes Store, read some reviews and the XE one came out tops. Better still, it’s free!
Other than conversion, it also allows for exchange data trends. Geeky, yes but gives you some insight to how volatile the markets can be on a daily basis.
Download it from XE directly http://www.xe.com/mobile/