Questions 23 to 26 are based on the following passage． American money can be quite confusing．The bills or paper money are all of the same color and size．One has to look carefully to he sure he is giving out a $1 bill and not a$10 bill，for example．Furthermore，new bills stick together easily，Be sure this does not happen to you．Coins are also confusing．This is partly because some of them have two names，partly because the size does not indicate the value．The ten．cent coin is smaller than the five—cent coin，for example．In addition，all coins are silver—colored except the penny(one cent)which is brown color or copper-colored． One cent，or a penny，is the coin of smallest value，equal to 1/100 of a dollar．It is useful for some parking meters and some sales taxes but a penny does not buy very much! Five pennies are equal to one nickel．A coin of ten cents，the smallest in size of all the coins，is one of the most useful．It is used for pay-phones，buying newspapers from coin—operated machines， and some bus fares．the 25-cent coin，or quarter，is larger than the nickel but is easily mistaken for it．This is the normal tipping coin，also commonly used for paying bridge and road tolls． One has to keep considerable change on hand，especially in cities which require exact change for their buses．Sales taxes also require a lot of small coins，although stores will give change．Bus drivers，however，are often not allowed to give change in many cities． Bills come in the following denominations(面额)：$1，$5，$10 and$20．They also come in$50 and$100 bills．but these are seen less often by most of us! Keep small-value bills with you．Taxi drivers and some store clerks will not change anything larger than a$5 bill; most big department stores will，however． How many denominations do we find in American bills according to the passage（）