One example of hyperinflation is in Germany in the 1920s. In 1922, the largest bank note was 50,000 Reichsmark, In 1923 the largest bank note was 100,000,000,000,000 Mark. In December of 1923 the exchange rate was 4,200,000,000,000 Marks to 1 US dollar. These bank notes were so worthless that people would burn them in fires to keep them warm. The notes would burn longer than the amount of wood you could buy with them. Sometimes the rate of inflation was so high that prices "doubled" every two days. The Rentenmark was introduced to stop this problem. The exchange rate was set at 4.2 Rentenmarks to 1 US Dollar.