The frequency thats flammable
Paper money the invention that can rip
Paper money was invented in China in 1017. They made it by wood block printing. One reason why paper money was an important invention was how much it is used today. Paper money is used in almost every country. About 100 countries use paper money. There are only about 120 countries in the world. The second reason I think paper money is useful is how much easer it is than coins. Coins are small and hard to keep track off. It is easer to keep a lot of paper money than coins because when you stack money it doesn't take up a lot of room. Coins are thick and can't be stacked. Money can be printed but coins are made of metal so it is not as easy. The paper money is all more useful.