Fun Economics: The Big Mac IndexThe words "fun" and "economics" usually don't go together in everyday language but this one is different. By using the Big Mac (Yes McDonald's famous Hamburger!) The Economist magazine was able to show how to measure the differences in the cost of living of different countries by comparing the different prices of the hamburger product.
It is fun and interesting.
Economist.com | The Big Mac Index
If you want to read more about the theory of puchasing-power parity, the article below gives a good explanation.
A Beginner's Guide to Purchasing Power Parity Theory (PPP Theory)