[jacquesm]

In the time before the wall fell most communist countries had an 'official' (ridiculous) and a black market exchange rate much like the one in the article. You were forced to exchange a certain amount of money for every day of your stay at the official rate, if you managed to smuggle just a few extra notes into the country and exchanged those on the black market it would usually translate into 'more money than you can sensibly spend'.

The reason those black markets are so popular is that people living in a country like that far prefer to hold on to some hard currency instead of the local currency which is devaluating so fast that even a few weeks can make a huge difference. Saving the local currency makes no sense and hence the black market materializes.

One person I know paid off a mortgage entered into a few years earlier with a single months pay, rapid inflation creates all kinds of havoc.