Highest monthly inflation: 29,500%
Prices doubled every: 3.7 days
Hyperinflation was one of the major problems plaguing Germany's Weimar republic during its last years of existence. Reaching a monthly inflation rate of approximately 29,500 percent in October 1923, and with an equivalent daily rate of 20.9 percent it took approximately 3.7 days for prices to double.
The German papiermark, which was introduced in 1914 when the country's gold standard was eliminated, began with an exchange rate of 4.2 per US dollar at the outbreak of WWI up to 1 million per US dollar in August 1923. By November, that number had skyrocketed to about 238 million papiermark to 1 US dollar, and a psychological disorder called "Zero Stroke" was coined, after people were forced to transact in the hundreds of billions for every day items and were dizzied by the amount of zeros involved.
The rapid inflation caused the government to issue a redenomination, thus replacing the papiermark with the rentenmark, exchanging at a rate of 4.2 per US dollar and cutting 12 zeros off of the papiermark's face value. Although the retenmark effectively stabilized the currency and the Weimar republic continued to exist until 1933, hyperinflation and its resulting economic pressures contributed to the rise of the Nazi party and Adolf Hitler, who focused explicitly on Germany's economic situation in Mein Kampf.