I was taught in Elementary School that the order of the operands does not change the result. However, this doesn't seem to hold true at easyjet website.

1. Go to www.easyjet.com and book the following:

June 6: GVA-ATH
June 8: ATH-FCO

Total price: 153.96 CHF ~ 162 USD

2. Restart the browser, go back to www.easyjet.con and book the same flights with the same dates, but start with the one from ATH-FCO

Total price = 134.77 EUR ~ 175 USD!

So, it looks like the final price is different depending on the "default" currency of the transaction. Also, if I let easyjet to quote the prices in USD I'm charged about $4 more, but this is not surprise as it's almost always better let your bank to to the conversion.