Your eyes do not deceive—the currency pictured is a note for 100 trillion Zimbabwean dollars. Steve H. Hanke, Johns Hopkins professor of applied economics in the Whiting School of Engineering, recently studied the hyperinflation that produced the note. Zimbabwe ceased reporting most economic data in 2008, but Hanke used an economic principle called purchasing power parity—the first time that’s ever been done, he says—to calculate that in November 2008 the country’s monthly inflation rate reached an astounding 79.6 billion percent.