In 1983 the Zimbabwean Dollar was equal to the US Dollar, USD$1 == Z$1.
By mid-2006 it had devalued to USD$1 == Z$500,000+.
In 2008, USD$1 == Z$750,000,000,000+ (750 billion).
In 2009 the currency was abandoned altogether and the US Dollar was adopted as the official currency. The Z$ which once had value now had none, where did that value go?
For instance, let's say in 1983 two Zimbabweans each decide to put some money away for retirement. A poor farmer stuffs Z$100 into a mattress, and a wealthy business owner puts Z$1,000,000 into a savings account. By 2009 hyperinflation has reduced both of their savings plans to nothing.
The wealthy business owner may have accountants or advisors who warn him to convert his savings to hard assets before it becomes worthless. The farmer doesn't have this luxury, he and the millions of other commoners like him hold their meager wealth in cash or other dollar-denominated assets, and they all lose everything. Where did it go?
The foreign currencies being used now have value, the government of Zimbabwe obviously can't just print USD$ like they did Z$, so where did this new currency come from and how could it even get into people's hands when most of the population had been economically zeroed out?
"Zimbabwe $100 trillion 2009 Obverse" by Reserve Bank of Zimbabwe - Self-scan by (Marianian) followed by minor Photoshop enhancements to improve appearance and reduce size. Second version scan by (Camp0s) with original color preserved. Transferred from en.wikipedia to Commons by User:Avicennasis using CommonsHelper.. Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Zimbabwe_$100_trillion_2009_Obverse.jpg#/media/File:Zimbabwe_$100_trillion_2009_Obverse.jpg